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59 Cards in this Set

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  • Back
What is anemia?
A decrease in red cell mass
What lab values do we use to measure anemia?
hemoglobin (Hg) or hematocrit (HCT)
What values of hemoglobin define anemia in men and women?
Hg less than 12 in women
Hg less than 13 in men
Hemotocrit is roughly how many times that of hemoglobin?
3 times
When would hemoglobin and HCT become falsely elevated?
When the patient is dehydrated (Hg and Hct are plasma volume-dependent)
When would hemoglobin and HCT become falsely decreased?
When the patient has volume over load (e.g. cirrhosis or CHF)
In what 3 situations does anemia occur?
1. Blood loss is the most common cause (usually from GI bleed or menses)
2. Inadequate production of RBCs
3. Excessive destruction of RBCs (intravascular or extravascular)
What causes inadequate production of RBC?
1. If bone marrow does not have the necessary building blocks such as iron or vit B12
2. If the bone marrow is damaged due to drugs, fibrosis or cancer infiltration
Where are the two places where RBCs can be destroyed?
Hemolysis can occur either within the blood vessels (intravascular) or in the spleen (extravascular)
How do the reticulocyte count and MCV help to determine the etiology of anemia?
The normal bone marrow responds to anemia by releasing reticulocytes. With hemolysis or acute blood loss, the retic count increases. A normal marrow response is reflected in a corrected reticulocyte index of greater than 2-3.
What does a low corrected retic count (lower than 2-3) indicate?
The bone marrow is not functioning normally, meaning there a production problem. At this point, you look at the MCV to distinguish the cause.
What does MCV mean?
mean cell volume
What is the normal retic count?
1%, meaning there is approximately 1 reticulocyte for 100 rbcs. Note that this number must be adjusted (corrected) for hematocrit
How do you calculate a corrected retic count?
% reticulocytes x (patient's Hct/normal Hct)
What causes macrocytosis, an MCV greater than 95?
Enlarged red cells often develop when abnormal DNA synthesis delays nuclear maturation of erythrocyte precursors, as in B12 or folate deficiency. Alcohol may be the most common cause of macrocytic anemia. Alcohol has a direct effect on the bone marrow.
What percentage of alcoholics have an MCV greater than 100?
49% to 90%
What causes microcytosis, an MCV less than 80?
Small red cells occur with problems in hemoglobin synthesis, as with iron deficiency or thalassemia.
How do people get deficient of folate?
1. Not ingesting enough: inadequate intake of leafy green vegetables and citrus fruits. You see this in severely disabled people and alcoholics.
2. problems with absorption: small bowel disease or use of phenytoin or phenobarbital NOTE: common anti-epileptic drugs impair folate absorption
3. increase demand: pregnancy, psoriasis, chemotherapy or hemolytic anemia
How long does the body store folate?
3 months
How long does the liver store vit B12?
3-5 years, so nutritional deficiency almost never occurs
What protein does vit B12 require in order to be absorbed?
Vitamin B12 requires binding to intrinsic factor (IF) made in the stomach in order to be absorbed in the terminal ileum.
What is vit B12 deficiency generally due to?
Deficiency is usually caused by:
1. pernicious anemia (destruction of the parietal cells that make intrinsic factor in the stomach)
2. achlorhydia: loss of stomach acid, common in older patients and leads to deficiency by preventing binding of B12 to IF
3. Colchicine (treatment of gout) and neomycin (topical antibiotic) can also block B12 absorption
What signs and symptoms does vitamin B12 deficiency cause?
nausea, heartburn, vague abdominal pain, depression, subacute neurologic disease (dementia, dorsal and lateral column defects)
What is anemia of chronic disease?
Also known as inflammatory block. It is a mild to moderate anemia resulting from an inability to utilize iron. Inflammatory mediators prevent the normal transfer of iron from bone marrow stores into hemoglobin?
In what conditions do you see anemia of chronic disease?
rheumatoid arthritis, SLE, chronic infections such as osteomyelitis
What causes intravascular hemolysis?
RBCs are broken down directly in the blood vessels. Examples include: RBC fragmentation across mechanical heart valves or over fibrin strands in DIC.
What causes extravascular hemolysis?
Abnormal RBCs are lysed in the reticuloendothelial system (RES) of spleen or liver. RBCs are recognized as abnormal when they have attached antibodies (such as autoimmune hemolysis or infection) or membrane or hemoglobin defects such as sickle cell disease or thalassemia.
What medications cause anemia?
Always review a patient's med list in unexplained anemia. Common drugs associated with anemia are anticonvulsants, colchicine, trimethoprim, chloroquine, and certain antibiotics. Pioglitazone and rosiglitazone can cause a dilutional anemia.
T or F: Asymptomatic patients should not be screened for anemia.
In whom should I suspect anemia?
Patients with fatigue, shortness of breath, dyspnea on exertion, dizziness, pallor or tachycardia. These symptoms are nonspecific and reflect inadequate oxygen delivery.
What should I look for when I evaluate patients with anemia? (History and Physical)
History: A history of chest pain, lightheadedness or shortness of breath that indicates possible end-organ hypoxia.
Physical: You should also look for tachycardia, cardiac flow murmur, pale conjunctivae, pale palmar creases and pale nail beds.
What tests are key in differentiating types of anemia?
Order an HCT or hemoglobin to confirm the diagnosis of anemia. Retic count, MCV and peripheral smear will suggest a diagnosis or need for further testing.
How does a perpheral smear differentiate between intra and extravascular hemolysis?
Spherocytes are formed during extravascular hemolysis when abnormal red cell membrane is removed by the RES. Irregularly shaped red cell fragments or schistocytes are formed as red cells sheer across intravascular obstacles such as prosthetic valves and fibrin strands.
T or F: Schistocytes are only seen in intravascular hemolysis.
What blood work measurements change when there is hemolysis (intra or extravascular)?
1. reticulocytosis
2. elevated indirect bilirubin
3. elevated LDH
4. decreased haptoglobin
Why does haptoglobin decrease in hemolysis?
Measurable haptoglobin drops because it binds to the hemoglobin released from hemolyzed red cells.
If I suspect iron deficiency, what else should I look for?
Ask about heavy menses, bloody or black stool, fatigue and pica (eating non-food items such as paper or clay).
What is pagophagia?
Pica for ice. It is considered a specific symptom for iron deficiency.
What is koilonychia?
spoon nails: an uncommon sign of iron deficiency
What is atrophic gastritis?
A smooth red tongue: an uncommon sign of iron deficiency
What lab studies do you do when you suspect iron deficiency anemia?
1. serum iron (low)
2. total iron binding capacity (high or normal)
3. ferritin (low)
What do you do if labs suggest iron deficiency?
You need to locate the source of blood loss. In addition to guaiac testing, endoscopy may be necessary.
What percent of anemias of chronic disease are normocytic?
What MCV values are considered normocytic?
MCV 80-95
What are the common and less common causes of normocytic anemia?
Common: anemia of chronic disease, acute bleeding

Less common: bone marrow supression, fibrosis or infiltration
What should I do next if my patient has normocytic anemia?
1. Think about anemia of chronic disease
2. Review meds that could suprress the bone marrow
3. Check for neoplastic disease
4. Do a peripheral smear that may suggest hemolysis or sickle cell disease. Marrow fibrosis or infiltration may lead to teardrops in the smear.
5. Bone marrow biopsy can rule out myelodysplasia, infiltration or bone marrow fibrosis
How do I treat iron deficiency anemia?
Replenish iron orally. 25% of patients will experience nausea, epigastric pain, constipation and diarrhea if they take iron on an empty stomach. Although absorption is decreased 40% when iron is taken with food, this may be a necessary compromise. Start with 325 mg of ferrous sulfate once a day and advance to twich a day as tolerated. Ferrous gluconate and elixir preparataions are available as well.
What response should I expect when a patient is on iron supplements?
The Hct should increase by 2 points every 3-4 weeks. A reticulocytosis is the first sign of response and is evident after 10 days.
When should I hospitalize a patient with anemia?
Hospitalize patients with anemia when they have a declining HCT due to ongoing blood loss or rapid hemolysis, or when cardiac or pulmonary symptoms occur.
What tests should I order if my patient has macrocytic anemia?
1. Review history for alcohol or medication use.
2. Review risk factors for and symptoms of vit B12 deficiency such as gastric surgery, vitiligo, paresthesias in the feet
3. Review for symptoms of hypothyroidism
4. Look for chronic liver disease
5. Look for signs or symptoms of acute bleeding or hemolysis because reticulocytes are larger than mature red cells and will raise the MCV
What MCV value indicates macrocytic anemia?
MCV greater than 95
What are common and less common causes of macrocytic anemia?
Common cause: alcohol

Less common cause: vit B12 deficiency, folate deficiency, hypothyroidism, reticulocytosis
What are signs of vit B12 deficiency?
beefy red tongue, decreased peripheral vibratory or position sense
The MCV is low and labs have rule out iron deficiency. What do I do next?
Consider anemai of chronic disease or thalassemia.
What do iron studies look like if you have anemia of chronic disease?
Ferritin (an acute phase reactant) is often high.
TIBC and serum iron are low. Despite low serum iron, iron replacement is no benefit because of the inflammatory block.
In what ethnic groups do you see thalassemia?
Mediterranean, African and Asian
What is the MCV range for patients with thalassemia?
MCV is low 60-70 range, and out of proportion to a mild anemia (Hct of 33-40).
What do you see on a peripheral smear in thalassemia?
target cells
What study can you perform to confirm a B-thalassemia?
Hemoglobin electrophoresis. There is no confirmatory test for alpha-thalassemia.