Nutritional Diseases

CASE 2: Megaloblastic Anemia

Clinical History:

A 48-year-old man has been tired and listless for the past 9 months. He lives alone in a small, run-down apartment near the downtown section of a large city. He is visited by a friend, who notes the presence of pizza delivery boxes scattered throughout the apartment, as well as a refrigerator containing 20 cans of beer and nothing else except for a pint of soured milk, half a loaf of stale bread with green patches, and an apple with something growing on it that is fuzzy and pink. The man states that he has had a feeling of nausea for months and as a consequence has a reduced appetite. On examination he has paresthesias of his lower legs. An upper GI endoscopy shows diffuse gastric rugal atrophy.

A CBC shows the following:

WBC count6190/uL
Hgb9.1 g/dL
MCV129 fL
Platelet count331,000/uL
  1. How do you interpret the CBC?

  2. The WBC count and platelet count are normal. The Hgb and Hct indicate anemia of a moderate degree. The high MCV indicates that this is a macrocytic (megaloblastic) anemia.

  3. What is the probable cause for these findings?

  4. Dietary deficiencies of either vitamin B12 (cobalamin) or folic acid (folate) can lead to this form of anemia. The hematopoietic cells, including the RBCs, are larger (megaloblastic) because B12 and folate are required for DNA synthesis, and nuclear maturation is impaired so fewer cell divisions occur and more cytoplasm is present. It is important to determine which nutrient is lacking (B12 and folate are ordered as a panel) because B12 deficiency can also result in neurologic damage (dorsal sensory and lateral motor spinal cord tracts). Folic acid deficiency alone leads to the macrocytic anemia, but no other major problems. The hint of a neurologic problem in this case (paresthesias) suggests vitamin B12 deficiency, which affects the posterior and lateral columns of the spinal cord. His gastric atrophy also suggests B12 deficiency, because intrinsic factor produced by parietal cells complexes with B12 and is absorbed in the distal ileum.

  5. How could you confirm your diagnosis?

  6. You must always measure both folate and B12 levels if ordering laboratory tests so you don't miss the B12 deficiency, which has more serious neurologic consequences if not treated.

    In this case, the findings might show:

    • Folate 5.1 ng/mL (2.8 - 17.8)

    • B12 88 pg/mL (210 - 911)

  7. What are dietary sources to alleviate this problem?

  8. Persons with a diet lacking in vegetables are at risk for folate deficiency. Folic acid is found in many green and yellow leafy vegetables. Since folate is not stored in the body, there must be a continuing dietary intake.

    B12 is found in many sources, especially meat and dairy products. The persons at greatest risk for a dietary deficiency are lacto-ovo-vegetarians, but even in these persons B12 deficiency is rare with a varied diet. Moreover, B12 is stored in the liver (several years' worth) so temporary dietary deficiencies have no major effect. Persons with some gastrointestinal diseases (atrophic gastritis, inflammatory bowel disease affecting the ileum) may have impaired absorbtion of B12.

  9. Is there a medication available to treat this condition?

  10. One can take vitamins with folate, or folate as a separate vitamin preparation. The same is true of B12. You can also give an intramuscular injection of B12.