Tetany is most directly associated with which electrolyte abnormality?

• A. Hyperkalemia
• B. Hyponatremia
• C. Hypocalcemia
• D. Hypermagnesemia

Answer: (C)

Tetany occurs when neuromuscular membranes become more excitable due to low calcium levels. Calcium normally helps stabilize nerve membranes and limit sodium influx; when calcium is low, nerves fire more readily, leading to muscle spasms and tingling sensations characteristic of tetany, such as carpopedal spasm and facial twitching (Chvostek sign). Among the options, hypocalcemia is the electrolyte abnormality most directly linked to this increased excitability.

Hyperkalemia changes conduction and can cause weakness or arrhythmias rather than tetany. Hyponatremia causes neuro symptoms like confusion or seizures but not the classic tetany. Hypermagnesemia tends to depress neuromuscular activity, producing weakness and decreased reflexes, not tetany.

In clinical practice, think of tetany with conditions causing low calcium, such as hypoparathyroidism, vitamin D deficiency, or after thyroid surgery. Managing it involves correcting calcium (often with IV calcium in acute cases) and addressing the underlying cause, while also checking ionized calcium for accuracy.