Renal and acid–base: potassium in diabetic ketoacidosis: practice question

A Physiology 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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Physiology · Renal and acid–base: potassium in diabetic ketoacidosis

Sample item

A patient in diabetic ketoacidosis has a serum potassium of 5.6 mmol/L on arrival, though total body potassium is depleted from osmotic diuresis. After starting insulin infusion, the serum potassium falls sharply. What is the mechanism of this fall?

AInsulin drives potassium into cells through stimulation of the Na-K ATPaseBInsulin increases renal potassium secretion aloneCInsulin lowers aldosterone secretionDInsulin inhibits potassium absorption in the gut

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

The answer and the reasoning

A. Insulin drives potassium into cells through stimulation of the Na-K ATPase

Insulin deficiency and hyperosmolality shift potassium out of cells, so serum potassium appears normal or high despite depletion of body stores. Insulin therapy stimulates Na-K ATPase in muscle and fat, moving potassium back into cells and unmasking the deficit, so potassium must be monitored and replaced.

Option by option

A. Insulin drives potassium into cells through stimulation of the Na-K ATPase (correct)
Correct. Insulin promotes cellular uptake of potassium.
B. Insulin increases renal potassium secretion alone
Renal potassium secretion is not the main effect of insulin and would not explain a rapid fall.
C. Insulin lowers aldosterone secretion
Insulin does not lower aldosterone secretion.
D. Insulin inhibits potassium absorption in the gut
Insulin does not inhibit potassium absorption in the gut.

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 Physiology question

What is the answer to this Physiology question?

The best answer is A, Insulin drives potassium into cells through stimulation of the Na-K ATPase. Insulin deficiency and hyperosmolality shift potassium out of cells, so serum potassium appears normal or high despite depletion of body stores.

Why is "Insulin increases renal potassium secretion alone" not the answer?

Renal potassium secretion is not the main effect of insulin and would not explain a rapid fall.

Why is "Insulin lowers aldosterone secretion" not the answer?

Insulin does not lower aldosterone secretion.

Why is "Insulin inhibits potassium absorption in the gut" not the answer?

Insulin does not inhibit potassium absorption in the gut.

What concept does this question test?

It tests Renal and acid–base: potassium in diabetic ketoacidosis in Physiology. Insulin therapy stimulates Na-K ATPase in muscle and fat, moving potassium back into cells and unmasking the deficit, so potassium must be monitored and replaced.

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 Renal and acid–base: potassium in diabetic ketoacidosis?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.