A 59-year-old woman comes to the office due to progressive fatigue and occasional heart palpitations over the last 6 months. The patient has been under a lot of stress recently due to problems at work. She has no dietary restrictions, eats out at restaurants frequently, and drinks 2 or 3 cans of beer on the weekends. The patient is postmenopausal and has not noticed any uterine bleeding, dark stools, or bleeding with bowel movements. Her BMI is 25 kg/m². Hemoglobin is 8.5 g/dL. Peripheral blood smear reveals pale, microcytic erythrocytes. Which of the following is the most likely underlying cause of this patient's abnormal laboratory findings?

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11ec160b_3984_369d_9249_0f394abec03f_MD0001_00 Fatigue and heart palpitations are common manifestations of all forms of anemia. This patient's peripheral smear findings indicate hypochromic, microcytic anemia, which most often arises in the setting of iron deficiency. The primary, and most dangerous if overlooked, mechanism of iron deficiency is blood loss, and it should be excluded first. Women of childbearing age are commonly iron deficient due to menstruation. Men (especially over the age of 60) or postmenopausal women have no physiologic reason to be iron deficient and therefore should be evaluated for blood loss in the gastrointestinal (GI) tract (eg, due to malignancy). GI blood loss is often occult, so the lack of dark or bright red stools in this patient should not rule out GI hemorrhage. Iron studies (including ferritin) should be obtained, and the patient will likely require endoscopic evaluation. (Choice A) Ingestion of the more commonly abused drugs is not associated with microcytic anemia. (Choice B) Hematologic malignancies (eg, leukemia, lymphoma, multiple myeloma) tend to be associated with normochromic, normocytic anemia. The decrease in erythropoiesis seen in these patients results from hypersplenism or tumor replacement of bone marrow mass. (Choice C) Hemolysis often presents with a normochromic, normocytic anemia. Spherocytes or schistocytes are often seen on peripheral blood smear. (Choice D) The anemia of chronic liver disease is usually normocytic or slightly macrocytic with target cells on the peripheral blood smear. Microcytic anemia occurs in <25% of cases, and most patients have only mild anemia with a hemoglobin level of 10-11 g/dL. (Choice F) This patient has a normal BMI and no factors predisposing her to malnutrition (eg, dietary restrictions, chronic alcohol use). A normal Western diet provides 6 mg of iron for every 1,000 calories, and the recommended intake for individuals age >50 is 8 mg per day. As a result, men and postmenopausal women (ie, not menstruating, pregnant, or lactating) usually have no dietary iron shortage. Educational objective: Hypochromic, microcytic anemia is most commonly due to iron deficiency. Blood loss, especially occult loss from the gastrointestinal tract, must be ruled out in a patient with iron deficiency anemia.

A 59-Year-Old Woman Comes to the Office Due to Progressive