Which condition is caused by defective copper reabsorption leading to low copper levels?

• A. Menke disease
• B. Wilson disease
• C. Hemochromatosis
• D. Hemosiderosis

Answer: (A)

Copper balance hinges on how well copper is absorbed and delivered to tissues. In Menke disease, a mutation in the ATP7A transporter disrupts intestinal uptake and distribution of copper, so copper cannot be absorbed effectively and systemic copper levels fall. Ceruloplasmin, which depends on adequate copper, also decreases, contributing to the deficiency. This explains low copper levels due to defective reabsorption/absorption. Wilson disease, by contrast, involves impaired excretion of copper into bile and into ceruloplasmin, leading to copper buildup rather than deficiency. The other two options are iron-related disorders, not copper metabolism, so they don’t fit the scenario.