American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the presumed cause of iron deficiency in men and nonmenstruating women?

1. Gastrointestinal blood loss

2. Dietary deficiency

3. Chronic kidney disease

4. Liver dysfunction

The correct answer is: Gastrointestinal blood loss

Iron deficiency in men and nonmenstruating women is primarily attributed to gastrointestinal blood loss. This population lacks the monthly iron loss seen in menstruating women, creating a different set of underlying causes for iron deficiency. Gastrointestinal bleeding can occur due to various factors, including peptic ulcers, malignancies, hemorrhoids, or chronic inflammatory conditions. In men and nonmenstruating women, exploring the gastrointestinal tract for potential sources of bleeding is essential when iron deficiency is diagnosed. This makes gastrointestinal blood loss the most relevant presumed cause in these cases, particularly since dietary deficiencies and other conditions like chronic kidney disease typically do not lead to iron deficiency without some form of blood loss. While liver dysfunction might affect iron metabolism and storage, it is not a direct cause of the typical iron deficiency seen in this demographic. Recognizing these details is crucial for correct diagnosis and management of iron deficiency in adults who do not have menstruation as a regular factor influencing their iron levels.