Lecture 27 - Macrocytic Anemias

Question 1

Macrocytic Anemias are characterized by MCV > _____ fL. If there are Megaloblastic characteristics such as Oval ______, Hypersegmented ______, or Pancytopenia, the first things that should be measured are serum _____ and vit ____.

Answer 1

MCV > 100 fL

Oval Macrocytes

Hypersegmented Neutrophils

Folate and Vit B12

Question 2

Macrocytic anemias that arise from Folate or B12 deficiency result in impaired _____ synthesis, and thus ineffective hematopoiesis. This is characterized in the Bone Marrow by RBC precursors showing ____-_____ asynchrony, and that are large/abnormal (aka megaloblasts). Megaloblastic characteristics of Peripheral Blood are Pancytopenia, Oval ______ (so increased MCV), and Hypersegmented _______ (6 or more lobes).

Answer 2

DNA synthesis

Nuclear-Cytplasmic asynchrony –> nucleus develops more slowly

Oval Macrocytes

Hypersegmented Neutrophils

Question 3

Folate deficiency can lead to characteristic neural tube defects in fetuses, an increase in _____ (direct or indirect?) bilirubin, and jaundice (bc of intramedullary hemolysis.) Keep in mind Folate is necessary for RBC uptake of vit ____. Be on the lookout for antifolate drugs like ______ and 5-fluorouracil in these patients. Also keep in mind Folate deficiency can develop quickly, in only a few _____.

Answer 3

Indirect bilirubin

Vit B12

Methotrexate

Months

Question 4

Vit B12 is also known as ______. It is synthesized exclusively by microorganisms in the _____. It is required for DNA and amino acid synth, _____ formation, and Folate interconversions. B12 deficiencies take long to develop, about 3-4 years. Keep in mind patients deficient in B12 exhibit more _______ disorders and ______ neuropathies than Folate deficient patients. Many patients deficient in B12 initially present with ONLY neurological symptoms without anemia. Think about who might experience B12 deficiency due to diet, remembering B12 comes from animal products (meats).

Answer 4

Cobalamin

Colon

Myelin formation

Neuropsych disorders

Demyelinating Neuropathies

Question 5

Absorption of B12 requires _____ factor produced by parietal cells in the intestine. Things like H. pylori infection or GI surgery could disrupt this.

Answer 5

Intrinsic Factor.

Question 6

Serum _______ acid (MMA) is measured to distinguish between Folate and B12 deficiency. It is elevated in B12 deficiency, but is normal in Folate deficiency.

Answer 6

Methylmalonic Acid (MMA)

Question 7

If a B12 deficiency has not been ruled out as the cause of megaloblastic anemia, what should the treatment be, and what is the issue with giving Folate ONLY?

Answer 7

Treatment should include B12 AND Folate. Giving Folate only would treat the anemia, but it would NOT halt the neurologic damage.