Endocrinology: post-thyroidectomy hypocalcaemia: practice question

A General Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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General Medicine · Endocrinology: post-thyroidectomy hypocalcaemia

Sample item

Two days after total thyroidectomy, a 45-year-old woman has perioral numbness and carpopedal spasm. Her serum calcium is 6.8 mg/dL. The ECG would be expected to show a prolonged QT interval. What is the best immediate treatment?

AIntravenous calcium gluconateBOral calcium carbonate alone, reviewing in one weekCA thiazide diureticDIntravenous magnesium and phenytoin

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Intravenous calcium gluconate

Hypoparathyroidism after thyroidectomy results from damage to or devascularisation of the parathyroid glands. Symptomatic hypocalcaemia with tetany needs intravenous calcium gluconate, followed by oral calcium and calcitriol. Hypocalcaemia prolongs the ST segment and QT interval and can cause laryngospasm and seizures.

Option by option

A. Intravenous calcium gluconate (correct)
IV calcium gluconate rapidly reverses tetany and prevents arrhythmia or laryngospasm.
B. Oral calcium carbonate alone, reviewing in one week
Oral calcium alone is too slow in symptomatic severe hypocalcaemia.
C. A thiazide diuretic
Thiazides reduce urinary calcium loss in chronic hypoparathyroidism but would not treat an acute tetany.
D. Intravenous magnesium and phenytoin
Phenytoin does not treat tetany, and magnesium is useful only if magnesium deficiency coexists.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this General Medicine question

What is the answer to this General Medicine question?

The best answer is A, Intravenous calcium gluconate. Hypoparathyroidism after thyroidectomy results from damage to or devascularisation of the parathyroid glands.

Why is "Oral calcium carbonate alone, reviewing in one week" not the answer?

Oral calcium alone is too slow in symptomatic severe hypocalcaemia.

Why is "A thiazide diuretic" not the answer?

Thiazides reduce urinary calcium loss in chronic hypoparathyroidism but would not treat an acute tetany.

Why is "Intravenous magnesium and phenytoin" not the answer?

Phenytoin does not treat tetany, and magnesium is useful only if magnesium deficiency coexists.

What concept does this question test?

It tests Endocrinology: post-thyroidectomy hypocalcaemia in General Medicine. Symptomatic hypocalcaemia with tetany needs intravenous calcium gluconate, followed by oral calcium and calcitriol. Hypocalcaemia prolongs the ST segment and QT interval and can cause laryngospasm and seizures.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Endocrinology: post-thyroidectomy hypocalcaemia?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.