B12, Folate And Iron Metabolism And Disease

Front 1

Without a sufficient supply of what two things, is DNA synthesis impaired and megaloblastic anemia occurs?

Back 1

Vitamin B12 and folate!

Front 2

These two vitamins are necessary for the formation of thymidine.

Back 2

Vitamin B12 and folate

Front 3

B12 is often obtained through diet via consumption of....
Do we have small or large stores of B12?

Back 3

B12 is thru consumption of animal products (meat and dairy); and most adults have LARGE stores of Vit B12 (mostly in liver) that can last for several YEARS.

Front 4

Describe the absorption of B12 into the body.

Back 4

Absorption requires salivary, stomach and pancreatic proteins: PEPSIN in stomach release Vit B12 from food. SALIVARY PROTEINS (R-binders), combine with free vitamin B12. In duodenum, PANCREATIC PROTEASES release B12 from R-binders and B12- then associates with INTRINSIC FACTORS (made from parietal cells in fundus in stomach), B12:IF is transported to ILEUM where it is absorbed.

Front 5

Deficiency in VitB12 can be due to:
A. Pernicious anemia
B. Inqdequate pepsin secreiton
C. Loss of exocrine pancreas funciton
D. Ileal disease
E. Increased requirements as in: pregnancy, lactation, hemolytic anemia.

Back 5

A. Pernicious anemia
B. Inqdequate pepsin secreiton
C. Loss of exocrine pancreas funciton
D. Ileal disease

note E is how you can get a folate deficiency
E. Increased requirements as in: pregnancy, lactation, hemolytic anemia

Front 6

In VitB12 deficient states _________ is elevated ; in folic acid deficient states _________ is elevated.

A. homocystine
B. methylmalonic acid
C. both homocysteine and methylmalonic acid

Back 6

VitB12 - C. both homocysteine and methylmalonic acid

Folate - A. homocystine

Front 7

Though folate administration can potentially correct anemia due to Vit B12 deficiency, why should it not be done alone to treat Vit B12 deficiency?

Back 7

Because it does nothing to alleviate the neurological damage that can occur with Vit B12 deficiency.

VitB12 deficiency can lead to subacute combined degen of spinal cord. Symptoms being: numbness, tingling, loss of vibratory sensation, loss of position sense, and spastic weakness. Complete paraplegia can develop if deficiency remains untreated.

Front 8

What is the most common cause of VitB12 deficiency?
A. Inadequate pepsin secretion
B. Ileal disease
C. Loss of exocrine pancreas function
D. pernicious anemia

Back 8

D. pernicious anemia

Pernicious anemia is immunologic destruction of the gastric mucosa, resulting in parietal cell loss and therefore lack of intrinsic factor. Is associated with other autoimmune disorders such as Hashimoto's thyroiditis.

Front 9

Pernicious anemia is the most common cause of _______.
A. Vitamin B12 deficiency
B. folate deficiency
C. iron deficiency

Back 9

A. Vitamin B12 deficiency

Front 10

Where is B12 absobed in body? Folate?

Back 10

B12 - ileum
Folate - jejeunum

Front 11

Decreased intake of B12 is found in what population whereas decreased intake of folate occurs in what population?

Back 11

B12 - in strict vegetarians and vegans
Folate - in chronic alcoholics and elderly

Front 12

Folate deficiencies are due to:
A. pernicious anemia
B. decreased intake, as in with alcoholics and elderly
C. jejunum disease or resection
D. increased requirements such as with pregnancy, lactation and hemolytic anemia
E. ileal disease or resection

Back 12

Folate deficiency can occur with the following:
B. decreased intake, as in with alcoholics and elderly
C. jejunum disease or resection
D. increased requirements such as with pregnancy, lactation and hemolytic anemia

Front 13

Describe folate metabolism in the body.

Back 13

Folate enters the body as Tetrahydrofolate (THF) and is immediately methylated. For THF to participate in DNA synthesis, it needs to get rid of methylation so it passes the methyl group to VitB12 who passes it to homocystine to make methionine.

Front 14

Explain why in both VitB12 deficiency and folate deficiency homocysteine levels are elveated.

Back 14

Folate enters the body as Tetrahydrofolate (THF) and is immediately methylated. For THF to participate in DNA synthesis, it needs to get rid of methylation so it passes the methyl group to VitB12 who passes it to homocystine to make methionine.

Front 15

What are the findings of B12 and folate deficiency in the peripheral blood?
A) What type of anemia: hypo, normo, hyper chromic and micro, normo, or macro cytic?
B. reticulocyte count: low or high?
C. hypersegmented __________
D. and general _____________

Back 15

A) What type of anemia: normochromic macrocytic anemia
B. reticulocyte count: low
C. hypersegmented neutrophils
D. and general pancytopenia

Front 16

True or False:
In megaloblastic anemia, hypercellular bone marrow is often seen despite sometimes seeing pancytopenia in peripheral smear.

Back 16

True.

This is because these patients have ineffective hematopoeisis, meaning that abundant myeloid and erythroid precursors are being destroyed before reaching peripheral blood.

Front 17

Regarding treatment of VitB12 or folate deficiency, iron levels fall within minutes as effective red cell production is re-initiated, the reticulocyte level increases within _______, and hemoglobin level increases within ________.

Back 17

reticulocyte level increases within 1-3 days ;
hemoglobin level increases within about a week

Front 18

True or False:
There is no physiological mechanism to regulate iron loss.

Back 18

TRUE!

Though iron uptake is highly regulated.

Front 19

Where does iron uptake occur in GI tract?

Back 19

duodenum and early jujenum mainly though occurs thru all of small intestines area

Front 20

Iron absorption is controlled by intestinal mucosal cells of small intestine (particularly early jejunum). Upon absorption, iron can enter blood circulation or be stored in the mucosal cell itself.
A. If iron stores are high, how much goes into circulation when absorbed?
B. How about if iron stores are low?

Back 20

A. If iron stores are high, little absorbed will go into circulation
B. If iron stores are low, more absorbed will go into circulation.

Front 21

What does hepcidin do?

Back 21

Influences release of iron from the RES. Increased hepcidin = decreased iron release from RES. Decreased hepcidin = increased iron release from RES.

Front 22

Differential diagnosis of hypochromic, microcytic anemia include...? (4)

Back 22

1. Iron deficiency anemia
2. Anemia of Chronic Disease (anemia of impaired utilization; body has iron but can't utilize it correctly - as in chronic inflammatory diseases, malignancies)
3. Sideroblastic anemia (also impaired utilization. diminished heme synthesis which leads to uncreased uptake of iron by normoblast. The iron is deposited in the mitochondria (toxic effect!) leading to ineffective erythropoesis. Ringed sideroblasts occur in Prussian blue stains.
4. Thalassemias

Front 23

What type of stain is used to see ringed sideroblasts?

Back 23

Prussian blue

Front 24

What are the GI symptoms of abdominal pain, nausea, vomiting) followed by systemic toxicity (cardiovascular collapse, coma, hepatic necrosis) mostly in children indicative of? (Acute_______ poisoning).

Back 24

Acute iron poisoning.

Treatment: whole bowel irrigation, deferoxamine, deferasiroz, supportive measures.