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241 Cards in this Set
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def--> anemia
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reduction of the total circulating RBCs below normal limits
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what tests are used to Dx anemia
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Hct and Hg conc
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cause of most microcytic hypochromic anemias
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dec Hg synth(iron def)
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cause of most macrocytic anemias
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abnormalities that impair matuation of erythroid precursors in the bone marrow
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effects of hypoxia on the liver, heart, and kidney
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fatty changes
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effects of anemia on the CNS
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hypoxia that causes headache, dimness of vision, and faintness
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effects of EPO
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stim the prolif of committed erythroid progenitors(CFU-E) in the marrow
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how long before the effects of EPO happen
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5 days
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effects of bleeding on WBCs
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the compensatory release of adrenergic hormones mobilizes granulocytes from the intravascular marginal pool and results in leukocytosis
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effects of hemorrhage on retic count
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inc retics after 5 days
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histologic differences of RBCs and retics
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retics are larger and have blue-red polychromatophilic cytoplasm
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what are the effects of blood loss on platelets
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thrombocytosis due to inc production
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normal life span of an RBC
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120 days
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where RBC destruction normally happens
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in the mononuclear phagocytes of the spleen, liver, and BM
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extravascular hemolysis
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when phagocytes eats RBCs before they are supposed to, due to changes that cause RBCs to be less deformable
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Sx of extravascular hemolysis
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splenomegally due to hyperplasia of phagocytes
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effects of Hg leaking out of phagocytes and into the blood
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dec haptoglobin(binds free Hg and prevents its excretion in the urine)
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causes of intravascular hemolysis
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mechanical injury
complement fixation intracellular parasites exogenous toxic factors |
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cause of toxic injury to RBCs
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clostridial sepsis
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lab Sx of intravascular hemolysis
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anemia, hemoglobinemia, hemoglobinuria, hemosidurinuria, and jaundice
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lab Sx of extravascular hemolysis
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anemia, splenomegaly, jaundice
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what causes the brown urine in hemolytic anemia
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the free Hg is oxidized to metHg(which is brown) which can't all be captured in the kidney tubules and some leaks into the urine
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cause of renal hemosiderosis
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Fe from Hg in hemolytic anemia accumulates in the tubular cells
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where and how the Hg is catabolized to billirubin in hemolytic anemia
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phagocytes as unconjugated bilirubin
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why hemolytic anemia can cause gallstones
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the liver excretes the conjugated bilirubin into the bile. The heme pigments can form stones in the ducts which cause gallstones
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where extramedullary hematopoiesis can occur in severe anemia
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liver, spleen, and LNs
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cholelithiasis
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pigment gallstones
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cause of hereditary spherocytosis
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intrinsic defects in the RBC membrane skeleton that render them speroid, less deformable, and vulnerable to splenic sequestration and destruction
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inheritance pattern of HS
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autosomal dominant
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how long the RBC life span is shortened in HS
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10-20 days
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proteins affected by HS
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anktrin, band 3, spectrin, or band 4.2; these are all involved in the first of the 2 tethering interactions
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mutations commonly seen in HS
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shifts in reading frame, stop codons
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effects of HS on RBCs as they age
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they have a reduced stability of their lipid bilayer that leads to loss of membrane fragments as the RBCs agi in circulation; this forces them to assume the smallest possible diameter for a given volume(sphere)
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where do RBCs of HS get trapped in the spleen
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in the cords of billroth
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effects of splenectomy on HS
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the spherocytosis persists but the anemia is corrected
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distinguishing feature of HS when compared to other hemolytic anemias
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it produces a larger splenic enlargement
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what causes the splenomegally in HS
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congestion of the cords of billroth and inc numbers of phagocytes needed to clear the spherocytes
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clinical feat of HS when testing the blood
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RBCs that are abnormally sensitive to osmotic lysis when placed in hypotonic salt solutions andan inc MCHC due to dehydration from the loss of K+ and H2O
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what causes the aplastic crises in HS
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parvovirus that infection and kills RBC progenitors which lasts until an immune response can be mounted
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common cause of hemolytic crises in HS
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infectious mononucleosis
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what pathways protect RBCs from oxidative injuries
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hexose monophosphate shunt and glutathione metabolism
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effect of G6PD def
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NADP cant be reduced to NADPH which is needed to reduce glutathione which protects against oxidant injury by catalyzing the breakdown of H2O2 and other radicals
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why G6PD is more prevelant in males
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it is a recessive X-linked trait
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why is the G6PD- gene helpful
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it is protective against Plasmodium falciparum malaria
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what is the pathogenesis of G6PD variants assoc with hemolytic anemia
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misfolding of a protein that makes it more susceptible to degradation
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most coomon trigger of G6PD hemolysis
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infections due to the oxidative stress they create
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most common infection assoc with G6PD hemolysis
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viral hepatitis, pneumonia, and typhoid fever
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drugs that are assoc with G6PD hemolysis
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antimalarials, sulfonamides, nitrofurantoins
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food that is assoc with G6PD hemolysis in the mediterranean variant
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fava bean
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type of hemolysis that happens win G6PD- people when oxidants are created
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intravascular and extravascular
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how high levels of oxidants creates hemolysis in G6PD def pts
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cross-linking of reactive sulfhydryl groups o the globin chains, which become denatured and form membrane-bound precipitates known as Heinz bodies
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Heinz bodies
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dark inclusions(when stained with crystal violet) that can cause membrane damage and hemolysis in G6PD- pts
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lab test abnormalities in pts with G6PD- when oxidants are introduced
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anemia, hemoglobinemia, and hemoglobinuria
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what G6PD variant has the worst hemolysis
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the mediterranean variant
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why are G6PD hemolytic episodes self limited
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only the older RBCs are vulnerable
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why there is no splenomegally or cholelithiasis in pts with G6PD-
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the hemolytic episodes are sporadic
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what is the mutation in sickle cell
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point mutation in the 6th codon of the β-globin that replaces a glutamate with a valine
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what does sickle cell trait protect against
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infection with falciparum malaria
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why RBCs in sickle cell sickle
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the HbS molecules polymerize when they are deoxygenated
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what % of Hb is HbS in pts with sickle cell trait
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40%
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what type of Hb is the most potent inhib of polymerization of HbS
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HbF
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what is the subsitution in HbC
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lysine for glutamate at the 6th codon
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what is the percentage of HbS in cells that are HbSC
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50%
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why are the conc of HbS higher in cells that are HbSC
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they tend to lose salt and water and become dehydrated
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if a pt with HbS has what disease as well are they less likely to be symptomatic
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α-Thalassemia because this dec the MCHC due to dec synth of Hb
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where does most of the sickling take place in the body
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in the slow moving vascular beds--> spleen and bone marrow
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what effect does sickling have on cellular ion conc
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the membrane distuptions enhance Ca entrance and this causes an inc in K and H2O effulx
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what correlates with the severity of hemolysis in sickle cell pts
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the percentage of irreversibly sickled cells
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why are the sickled cells more sticky in BVs
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they express higher than normal levels of adhesion molecules due to the inc in cytokines during the inflammation that occurs from vascular damage related to the disease
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what effect does NO play in sickle cell
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free Hg from lysed RBCs can bind and prevent NO from acting as a vasodilator which further inc the vascular occlusion due to platelet aggregation
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howell-jolly bodies
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they are the small nuclear remnants that are present in some RBCs in pts with asplenia and sickle cell
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why do pts with sickle cell have a crew-cut appearance on X ray
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they hyperplastic BM causes inc bone resorption and inc secondary bone formation in other bones especially of the cheeks and skull
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the type of gallstones in sickle cell
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pigment gallstones
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characteristics of the spleen in a young pt with sickle cell
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enlarged with red pulp congestion
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characteristics of the spleen in adolescents with sickle cell
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splenic infarction, fibrosis, and shrinkage(autosplenectomy)
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what is a Sx of sickle cell that can be present in adults but is absent in kids
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leg ulcers due to vascular stagnation in the subcutaneous tissues
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where do most vaso-occlusive crises happen in kids
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in the bones
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what is a sequestration crises
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when pts with sickle cell have rapid splenich enlargement, hypovolemia, and sometimes shock
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what causes aplastic crises in pts with sickle cell
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parvovirus B19 infection the BM
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what chemical is added to a blood sample to test for sickle cell
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metabisulfite
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the mainstay Tx for sickle cell
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hydroxyurea
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benefits of the Tx for sickle cell
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inc in HbF and inhib of WBCs so that there is an anti-inflammatory effect
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what is a thalassemia
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a disorder caused by a mutation that dec the synth of HbA
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where are the α-globin genes in the DNA
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chromosome 16
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where are the β-globin genes in the DNA
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chromosome 11
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what are the differences between β° mutations and β+ mutations in β-thalassemia
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β° is an absence in β-globin synth and the other is a reduction in synth
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most common gene defect in β+ thalassemias
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splicing mutations that lie within introns
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most common gene defect in β° thalassemias
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chain terminator mutations(premature stop codons or reading frame shifts)
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what is the main cause of RBC damage in β-thalassemias
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α chains precipitating and causing membrane damage
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cause of ineffective erythropoesis in β-thalassemias
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membrane damage of the precursors that cause apoptosis
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what anemia causes extraosseous masses in the thorax, abdomen, and pelvis
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β-thalassemia
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why is there an excessive inc in absorption of dietary iron in β-thalassemia
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ineffective erythropoesis suppresses the circulating levels of hepcidin
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β-thalassemia major
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a pt with 2 β-thalassemia alleles and is a transfusion-dependent anemia
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β-thalassemia minor
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a pt with 1 β-thalassemia allele and usually a microcytic asymptomatic anemia
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thalassemia intermedia
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when there is a α chain issue to go along with the β chain issue
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when β-thalassemia major Sx begin
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6-9 months after birth when the HbF production stops ans switches to HbA
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diseas that has target cells
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β-thalassemia major
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why the ritic count is elevated but not as high as expected for the severity of the anemia in a pt with β-thalassemia major
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there is defective erythropoesis
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what causes the spleen enlargement in β-thalassemia
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phagocyte hyperplasia and expansion of hematopoietically active marrow
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what are 2 Sx that occur in almost all pts with β-thalassemia
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hemosiderosis and secondary hemochromatosis, both are manifestations of iron overload
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what organs are most affected by the iron overload of β-thalaseemia
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heart, liver, and pancreas
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cure for β-thalassemia major
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BM transplant
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why HbA2 is inc in pts with β-thalassemia minor
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there is an elevated ratio of δ-chain to β-chain synth
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how β-thalassemia minor is differentiated from iron def anemia
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check the serum iron which is low in iron def
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how many α-globin genes are there
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4
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hemoglobin Barts
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the unpaired γ-globin chains in α-thalassemia form γ4 tetramers in newborns
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what is HbH
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the Hg that forms in older children and adults with α-thalassemia due to excess unpaired β-globin chains which from β4 tetramers
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why the hemolysis and ineffective erythropoiesis are less severe in α-thalassemia than in β-thalassemia
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the β and γ chains are more soluble than the α chains
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most common cause of reduced α-chain synth
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gene deletion
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silent carrier state of α-thalassemia
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when there is 1 α-chain gene deleted and the only symptom is mycrocytic RBCs
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α-thalassemia trait
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the deletion of 2 α-chain genes
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Hg H disease
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3 or more α-chain genes are deleted and the formation of HbH ensues
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why HbH causes hypoxia
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it has an extremely high affinity for O2
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why HbH inc phagocytosis of RBCs in the spleen
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once HbH is oxidized it precipitates and this inc phagocytosis
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hydrops fetalis
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deletion of all 4 α-chain genes
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what allows for survival of a fetus with hydrops fetalis
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there is production of ξ-chains that form functional ξ2γ2 Hb tetramers
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cure for hydrops fetalis
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BM transplant
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cause of paroxysmal nocturnal hemoglobinuria
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acq mutation in the phophatidylinositol glycan complementation group A gene(PIGA) which is an enzyme that is essential for synth of certain cell surface proteins
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the only hemolyitic anemia cause by an acq genetic defect
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PNH
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why PNH causes disease
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the normal membrane proteins are anchored to the membrane and the proteins attached to the membrane that anchor them are missing(glycosylphosphatidylinositol)
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why PNH occurs in RBCs, Platelets, and WBCs
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the mutation occurs in a hematopoietic stem cell causing all its progeny to have the defect
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what disease is assoc with PNH
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aplastic anemia
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what GPI-linked proteins that regulate complement are def in PNH
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decay accelerating factor(CD55), membrane inhibitor of reactive lysis(CD59), and C8 binding protein
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which complement protein in PNH is most important to the disease
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CD59 because it in C3 convertase and prevents activation of the Alt pathway
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why is there inc lysis at night in PNH
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there is an inc in pH during sleep that inc the activity of complement
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why PNH leads to iron def anemia
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in hemosiderinuria due to inc lysis
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leading cause of death in pts with PNH
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thrombosis
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effect of PNH on platelet fx
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puts them in a prothrombotic state
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cancers assoc with PNH
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acute myeloid leukemia and myelodysplastic syndrome
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cause of immunohemolytic anemia
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Ab are produced that bind to RBCs
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how immunohemolytic anemia is Dx
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direct Coombs antiglobulin test which detects Abs or complement attached to RBCs
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most commone form of immunohemolytic anemia
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warm Ab type
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Ab type in warm Ab type of immunohemolytic anemia and the type of hemolysis
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IgG and less commonly IgA; extravascular
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antigenic drugs that can cause immunohemolytic anemia
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Penicillin, cephalosporins, and quinidine when they bind to the cell membrane and are attacked by Abs
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difference in penecillin and quinidine hemolysis
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Pen is caused by Abs attached to the drug and Quinidine is due to Abs against a complex formed by the drug and the membrane
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how Abs against antigenic drugs cause hemolysis
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most commonly due to opsonization that causes phagocytosis extravascularly, but also rarely intravascularly due to complement
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what are tolerance breaking drugs and what is the prototype
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drugs that induce Ab creation against RBC Ags(Rh blood group Ags) and the prototype is α-methyldopa
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Abs in cold agglutination type of immunohemolytic anemia
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IgM
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infection that can cause cold agglutination type immunohemolytic anemia
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M. pneumoniae, EBV, CMV, and HIV
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vascular beds where cold agglutination hemolysis occurs
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those at a temp below 30°C--> fingers, toes, and ears
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how cold agglutination type hemolysis occurs
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the IgM bind but then fall off once the temp goes back up, but the C3b is usually already attached and this causes opsonization in the extravascular sites
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cause of cold hemolysin type immunohemolytic anemia
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IgG autoAbs bind to the P blood group Ag in the cool, peripheral regions of the body. This causes complement mediated lysis in the warmer parts of the body
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what is a common trigger for the cold hemolysin type hemolytic anemia in kids
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viral infection
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most common cause of hemolytic anemia due to trauma of RBCs
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artificial mechanical cardiac valves
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hemolytic anemia commonly seen with DIC
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microangiopathic hemolytic anemia
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diseases assoc with microangiopathic hemolytic anemia
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TTP, HUS, malignant HTN, SLE, and disseminated cancer
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cause of microangiopathic hemolytic anemia
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diseases that cause luminal narrowing which inc the shear forces on the RBCs
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characteristics of the blood smears in pts with microangiopathic hemolytic anemia
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red cell fragments(schistocytes), burr cells, helmet cells, and triangle cells
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most common anemia due to underproduction of RBCs
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nutritional def anemias
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cause of megaloblastic anemia
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B12 or folate def that cause dec DNA synth and large RBCs and their precursors
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roles of B12 and Folate in DNA synth
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they are needed for thymidine synth(one of the 4 nucleotides)
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morphology of RBCs in megaloblastic anemia
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they are macrocytic and oval, while they lack the central pallor of normal RBCs
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important feat of the CBC in pts with megaloblastic anemia
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retic count is low
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morphology of neutrophils in pts with megaloblastic anemia
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larger than normal and hypersegmented(5 or more segments)
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morhphology of the BM in megaloblastic anemia
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hypercellular with replacement of the fatty marrow
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effects of megaloblastic anemia on granulocyte precursors
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dysmaturation in the form of giant metamyelocytes and band forms
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cause of pancytopenia in megaloblastic anemia
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derangement in DNA synth causing most precursors in the marrow to undergo apoptosis
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cause of pernicious anemia
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autoimmune gastritis that cause a lack of IF production and therefore a lack of B12 absorption
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why vegetarians can develop pernicious anemia
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the veggies they eat don’t contain cobalmin which comes from microorganisms and is higher in animal foods than plant foods
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cells that secrete IF
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parietal cells of the fundic mucosa
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how B12 is freed from food and what picks it up after that
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pepsin frees it and salivary cobalophilins bind it in the stomach
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where B12 assoc with IF
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in the duodenum
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where the B12-IF complex is absorbed
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in the ileum
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what is the serum B12 transporer
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transcobalmin 2
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fxs of B12
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cofactor in the conversion of homocysteine to methionine by methionine synthase where it acts as a methyl acceptor to generate FH4 and it is a cofactor in the conversion of methymalonyl CoA to succinyl CoA
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what is the proximate cause of anemia in B12 def
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lack of folic acid
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what is inc in the blood during B12 def
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methylmalonic acid and homocysteine
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what causes the myelin breakdown in B12 def
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abnormal incorporation of FAs into neuronal lipids due to mthylmalonic acid buildup
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type 1 Abs in pernicious anemia
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those that block binding of B12 to IF
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type 2 Abs in pernicious anemia
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those that block binding of the B12-IF complex to the ileal receptor
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type 3 Abs in pernicious anemia
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those against the α and β subunits of the gastric proton pump in the microvilli of the parietal cells
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what is the initial cause of Abs to the gastric epithelium in pernicious anemia
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autoreactive T cells causing injury
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what innate immune receptor is assoc with pernicious anemia
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NALP1
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what other AI diseases are assoc with pernicious anemia
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AI thyroiditis and adrenalitis
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conditions in a pt that can cause a relative B12 def
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pregnancy, hyperthyroidism, disseminated cancer and chronic infection
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most common morphologic characteristic in pernicious anemia
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atrohpy of the fundic glands
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effects of pernicious anemia on the CNS
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demyelination of the spinal cord at the doral and lateral tracts; less commonly there is degen In the ganglia of the post roots and the periph nerves
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why B12 def inc the risk for vascular disease
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it inc the blood levels of homocysteine
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reactions that req FH4
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purine synth, conversion of homocysteine to methionine, and deoxythymidylate monophosphate synth
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what is the normal transport form of folate
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5-methylTHF
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drugs that interfere with the absorption of folate
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phenytoin and oral contraceptives
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how to differentiate between B12 def and folate def anemia
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in folate homocysteine is up and mthylmalonic acid is normal. In B12 both are up
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why you exclude B12 def as a cause of megaloblastic anemia before initiating folate therapy
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it can exacerbate the neurologic symtpoms of B12 def
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what type of iron is most absorbable In the diet
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heme iron
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what carries iron in the blood and where is it made
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Transferrin and in the liver
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how erythroid precursors absorbe iron
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they have transferrin receptors that induce endocytosis
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what is the storage protein for iron
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ferritin and hemosiderin
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where ferritin is stored in the lover
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parenchymal cells
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where ferritin is stored in the spleen and BM
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macrophages
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what is the basis for the prussian blue stain
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hemosiderin turns blue-black when exposed to K ferrocyanide
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what correlates well with the body iron stores
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ferritin levels
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how iron balance is maintained
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regulating the iron absorption in the proximal duodenum
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how iron is normally lost
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shedding of mucosal and skin epithelial cells
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what reduces Fe3+ iron to Fe2+
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ferrireductases(b cytochromes and STEAP3)
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what transports iron across the apical membrane of the intestine
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DMT1
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how iron corsses the basal membrane of the duodenum
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ferroportin 1 where it is then converted back to Fe3+ by hephaestin and ceruloplasmin
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where iron is stored in the cells
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lysosomes and cytosol
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what is the livers response to inc hepatic iron
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inc synth of hepcidin to dec iron absorption in the intestine
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how hepcidin works
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binds to ferroportin and causes it to be endocytosed and degraded
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cause of anemia of chronic disease
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inc levels of IL6 which stims the synth of hepcidin
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effect of mutation to TMPRSS6
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inc hepcidin synth even when iron levels are low
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syndrome where hepcidin is abnormally low
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hemochromatosis
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how much iron must be absorbed per day
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1g
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what enhances absorption of inorganic iron
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ascorbic acid, citric acid, Aas, and sugars
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what inhibs absorption of inorganic iron
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tannates(tea), carbonates, oxalates, and phosphates
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most commone cause of iron def in the western world
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chronic bloodloss
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when does anemia happen in iron def
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only when the iron stores are completely depleted
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effect of iron def on RBC morphology
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microcytic, hypochromic, and inc zone of pallor to 1/3 diameter, poikilocytosis in the form of small, elongated red cells(pencil cells) is also seen
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cause of koilonychia, alopecia, atrphy of the tongue and gastric mucisa and intestinal malabsorption in iron def
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depletion of iron containing enzymes throughout the body
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Plummer-Vinson syndrome
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esohphageal webs, mycrocytic hypochromic anemia, and atrophic glossitis
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Iron study results in anemia of chronic disease
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low serum iron, dec TIBC, and abundant stored iron in macrophages
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aplastic anemia
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failure of hematopoiesis and attendant pancytopenia
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most common cause of aplastic anemia
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drugs and chemical exposure
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drugs that can cause aplastic anemia
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chloramphenicol, gold salts, benzene, and chemotheurapeutic agents
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what virus can cause aplastic anemia
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Hepatitis of the non-A,B,C, or G types
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fanconi anemia
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rare autosomal recesive disorder caused by defects in a multiprotein complex that is req for DNA repair; there is also hypoplasia of the spleen, kidney, and bones(thumbs and radii)
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cells that are implicated in AI aplastic anemia
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Th1 cells producing IFN-γ and TNF which suppress and kill hematopoietic progenitors
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morphology of the BM in aplastic anemia
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devoid of hematopoietic cells; usually only fat cells, fibrous stroma, and scattered lymphocytes and plasma cells remain
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complication of multiple transfusions to Tx anemias
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hemosiderosis due to iron overload
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what Sx rules out aplastic anemia
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splenomegally
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what is a prominent feat of bood smears in aplastic anemia
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reticulocytopenia
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how to distinguish aplastic anemia from myeloid neoplasms
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the marrow is hypocellular in aplastic
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what is the cause of pure red cell aplasia
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AI basis where there is dec erythroid progenitors
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conditions assoc with pure red cell aplasia
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thymoma, large granular lymphocytic leukemia, drug exposure, AI disorders, and parvovirus infection
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what virus preferentially destroys red cell progenitors
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parvovirus B19
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myelophthisic anemia
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space occupying lesions replace normal marrow elements
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most common cause of myelophthisic anemia
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metestatic cancer from the breast, lung and prostate
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feat of blood smear in myelophthisic anemia
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nucleated erythroid precursors, immature granulocytic forms(leukoerythroblastosis), and teardrop-shaped red cells
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morphology of the BM in myelophthisic anemia
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distortion and fibrosis of the marrow which displace normal marrow elements that reg the egress of red cells and granulocytes from the marrow
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cause of anemia in renal failure
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dec EPO production and dec iron due to inc bleeding assoc with uremia
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what can be measured to asses the severity of the anemia in renal failure
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the severity of the uremia
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type of anemia in hypothyroidism
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mild normochromic, normocytic anemia
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type of anemia in hepatocellular liver disease
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slightly macrocytic due to red cells acq phospholipids and cholesterol in their membranes as they circulate
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polycythemia
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abnormally high red cell count
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cause of relative polycythemia
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dehydration
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Gaisbock syndrome
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a relative polycythemia called stress polycythemia
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Sx of gaisbock syndrome
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HTN, obese, and anxious(stressed)
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primary absolute polycythemia
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intrinsic abnormality of hematopoietic precursors
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secondary absolute polycythemia
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due to in EPO levels
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polycythemia vera
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the most common cause of primary polycythemia; a myeloproliferative disorder caused by mutations that lead to EPO-independent growth of RBC progenitors
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what factor plays a role in inc EPO secretion
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HIF-1α(stim transcription of the EPO gene)
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