A Routine CBC Leads to a Nonroutine Diagnosis.

A 20-year-old Hispanic female had 3 episodes of blood in her bowel movements, anal itching, burning, and constipation, and a history of hemorrhoids, hypothyroidism secondary to thyroiditis, depression, and an attempted suicide 3 months earlier. Family history was remarkable for iron deficiency anemia and hypothyroidism. Complete blood chemistry results indicated that she had vitamin B12 deficiency, but, except depression, did not exhibit other neuropsychiatric symptoms of cobalamin deficiency. A two-part Schiling test indicated that she was not producing adequate or active intrinsic factor, thus she was diagnosed with pernicious anemia and requires 1 mg of vitamin B12 intramuscularly for the rest of her life.