Electrolytes: thyrotoxic periodic paralysis: 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 · Electrolytes: thyrotoxic periodic paralysis

Sample item

A 28-year-old man wakes with sudden flaccid weakness of the legs after a carbohydrate-rich meal. Potassium is 2.1 mmol/L, heart rate is 120 per minute and TSH is suppressed. Which drug reduces recurrence of attacks until he is euthyroid?

ASalbutamolBA thiazide diureticCInsulin infusionDPropranolol

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

The answer and the reasoning

D. Propranolol

Thyrotoxic periodic paralysis is an intracellular potassium shift driven by adrenergic and insulin effects in hyperthyroidism, most common in Asian men. Non-selective beta-blockers such as propranolol prevent attacks, and cautious potassium replacement avoids rebound hyperkalaemia. Definitive treatment is control of the hyperthyroidism.

Option by option

A. Salbutamol
Salbutamol shifts potassium into cells and worsens hypokalaemia.
B. A thiazide diuretic
Thiazides cause potassium loss and would worsen it.
C. Insulin infusion
Insulin drives potassium into cells and can precipitate attacks.
D. Propranolol (correct)
Correct. Propranolol blocks the adrenergic drive and reduces attacks.

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 D, Propranolol. Thyrotoxic periodic paralysis is an intracellular potassium shift driven by adrenergic and insulin effects in hyperthyroidism, most common in Asian men.

Why is "Salbutamol" not the answer?

Salbutamol shifts potassium into cells and worsens hypokalaemia.

Why is "A thiazide diuretic" not the answer?

Thiazides cause potassium loss and would worsen it.

Why is "Insulin infusion" not the answer?

Insulin drives potassium into cells and can precipitate attacks.

What concept does this question test?

It tests Electrolytes: thyrotoxic periodic paralysis in General Medicine. Non-selective beta-blockers such as propranolol prevent attacks, and cautious potassium replacement avoids rebound hyperkalaemia. Definitive treatment is control of the hyperthyroidism.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Electrolytes: thyrotoxic periodic paralysis?

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.