A 50-year-old man comes to the office due to feeling fatigued and weak for a year. He becomes tired early in the day and also finds it difficult to remember things. He is currently unemployed and lives on Social Security benefits. The patient says that he drinks 2-3 beers a day but has been charged multiple times with driving under the influence. His parents died of old age. He lives with 4 friends. Vital signs are within normal limits. Laboratory results are as follows: Peripheral smear shows anisocytosis, poikilocytosis, and basophilic stippling. Which of the following is the best next step in management of this patient?

Question

A 50-year-old man comes to the office due to feeling fatigued and weak for a year.  He becomes tired early in the day and also finds it difficult to remember things.  He is currently unemployed and lives on Social Security benefits.  The patient says that he drinks 2-3 beers a day but has been charged multiple times with driving under the influence.  His parents died of old age.  He lives with 4 friends.  Vital signs are within normal limits.  Laboratory results are as follows:  Peripheral smear shows anisocytosis, poikilocytosis, and basophilic stippling.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d2e4_ce73_bc81_3752e91ea4bb_MD0003_00 This patient's presentation is consistent with macrocytic anemia, which is usually suggested by abnormal red blood cell (RBC) indices, including an elevated (ie, >100 µm³) mean corpuscular volume (MCV), elevated mean corpuscular hemoglobin (amount of hemoglobin in cell), and normal mean corpuscular hemoglobin concentration (low values are seen with microcytosis, elevated values are only seen with spherocytosis or some hemolytic anemias). Macrocytic anemia is due to 2 primary etiologies: ³ Megaloblastic (eg, impaired DNA synthesis due to B12 or folate deficiency): Typically associated with MCV >110 µm³, low reticulocyte count, macroovalocyte RBCs, hypersegmented neutrophils (mean lobe count >5), anisocytosis, and poikilocytosis. Nonmegaloblastic (eg, alcohol use, hypothyroidism, drugs, liver disease): Associated with increased, normal, or decreased reticulocyte count depending on the etiology. Therefore, the peripheral blood smear and reticulocyte count are helpful in distinguishing between the 2 etiologies. This patient's smear findings and MCV >110 µm³ favor megaloblastic anemia. Measuring B12 and folate levels can aid diagnosis and distinguish between B12 and folate deficiency. Patients with low levels usually require further testing to elucidate the underlying disorder. Pernicious anemia is the most important cause of B12 deficiency, and patients may also develop neurologic deficits (eg, memory loss) and achlorhydria. ³ (Choice A) Lead poisoning can be associated with basophilic stippling (ribosomal precipitates that form varying sizes of blue granules in the RBC cytoplasm); however, lead poisoning would cause microcytic (MCV <80 µm³) rather than macrocytic anemia. Basophilic stippling is nonspecific and can also be due to thalassemias or to alcohol use (as is likely in this patient). ³ (Choice B) Bone marrow biopsy is helpful for diagnosing myelodysplasia, which usually causes cytopenias in ≥1 cell lines. Although patients can develop macrocytosis, bone marrow biopsy is usually reserved for evaluating patients with normal B12 and folate levels. (Choice C) Direct antiglobulin test can help diagnose autoimmune hemolytic anemias. Patients typically have hemoglobin of 7-10 g/dL with elevated reticulocyte count, bilirubin, and lactate dehydrogenase. The haptoglobin is also markedly decreased, and peripheral smear usually shows spherocytes. However, it would not cause the significantly elevated MCV seen in this patient. (Choice D) Measuring iron levels is useful for evaluating patients with microcytic anemia (MCV <80 µm³). ³ Educational objective: Macrocytic anemia can be due to megaloblastic (eg, impaired DNA synthesis due to B12 or folate deficiency) or nonmegaloblastic (eg, alcohol use, hypothyroidism, drugs, liver disease) etiologies. Peripheral smear, reticulocyte count, and B12 and folate levels can aid diagnosis and distinguish between B12 and folate deficiency. References: Macrocytic anemia. (http://www.ncbi.nlm.nih.gov/pubmed/8546042)

A 50-Year-Old Man Comes to the Office Due to Feeling