USMLE (United States Medical Licensing Examination) Step 1 Practice Exam

What condition results in tetany, calcification of basal ganglia, and cataracts?

1. Hypomagnesemia

2. Primary B-cell lymphoma

3. Resp Alkylosis + Ca2+ Homeostasis

4. Primary hyperparathyroidism

The correct answer is: Hypomagnesemia

The condition characterized by tetany, calcification of the basal ganglia, and cataracts is primarily linked to hypomagnesemia. When magnesium levels are low, it plays a crucial role in regulating calcium homeostasis, which can lead to hypocalcemia, causing neuromuscular excitability resulting in symptoms such as tetany. The relationship of low magnesium and calcium levels can also lead to aberrations in calcium metabolism, causing calcifications in various brain structures, including the basal ganglia. Cataracts may develop due to the effects of magnesium deficiency on cellular metabolism, leading to oxidative stress and increased free radical formation, which damages lens proteins. This multifaceted impact on neuromuscular function, brain calcifications, and ocular health is consistent with the manifestations of hypomagnesemia. Other conditions presented would not typically yield all three symptoms combined as seen in hypomagnesemia. For instance, primary hyperparathyroidism primarily presents with hypercalcemia and symptoms associated with high calcium levels rather than hypomagnesemia-related manifestations.