MACROCYTIC anemias.

Abstract

Megaloblastic anemias result from processes that disrupt DNA synthesis. The condition is usually acquired, with medications, cobalamin, or folate deficiency being common precipitating factors. Many patients with cobalamin or folate deficiency will present with hematologic abnormalities, such as anemia or pancytopenia, along with macroovalocytes and hypersegmented neutrophils on the peripheral blood smear. Neuropsychiatric disturbances, such as peripheral neuropathy or depression, are also common with cobalamin or folate deficiency and may occur in the absence of significant hematologic manifestations. As these neuropsychiatric conditions are reversible if treated promptly by cobalamin or folate replenishment, a high degree of suspicion must be maintained when evaluating patients with unexplained neuropsychiatric abnormalities. Usually, the measurement of serum cobalamin or folate levels will be sufficient to make the diagnosis; the pitfalls of these and other tests are discussed. Inherited enzyme deficiencies are rare causes of megaloblastic anemia that should be considered after the more common acquired conditions are ruled out.