Pernicious Anemia Revisited

We discuss the pathophysiologic mechanisms, clinical features, diagnosis, and treatment of pernicious anemia (PA). A review of the clinical applications of the diagnostic and therapeutic progress of PA is presented. A patient with PA may have a wide range of initial complaints that affect various organ systems or may be entirely asymptomatic. Hematologic variables may be normal in patients with cobalamin (Cbl) deficiency. Because of the difficulties in diagnosing Cbl deficiency, alternatives to measuring Cbl have been sought. Determining the urinary methylmalonic acid level is a less invasive, more practical, and, possibly, more sensitive method. The Schilling test is performed for assessment of the absorption of orally ingested radiolabeled crystalline cyano-Cbl; results should be interpreted cautiously. Vitamin B₁₂ therapy should be lifelong. It is customarily administered intramuscularly. Other routes of administration have been studied. PA is one of the most treatable hematologic disorders.