All of the following are causes of polyuria except?

Appeared in: PGIMER NO - 2020

Explanation

Sympathetic stimulation, part of the 'fight or flight' response, leads to decreased urine output, a condition known as oliguria.
This occurs because it causes constriction of the afferent arterioles supplying the glomeruli, which reduces the glomerular filtration rate (GFR).
It also activates the renin-angiotensin-aldosterone system (RAAS), which promotes the reabsorption of sodium and water in the renal tubules, further conserving body fluid.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Regulation of urine output and causes of polyuria as background academic context rather than a clinical decision trigger.
Accurately identifying the cause of abnormal urine output is critical for patient management. Polyuria can lead to dehydration and electrolyte imbalances, while oliguria can signal acute kidney injury or severe volume depletion.
Nurses must meticulously monitor intake and output, especially in patients with endocrine disorders, those receiving diuretics, or critically ill patients, as changes in urine volume are often the first sign of a developing problem.
What if? If a patient with known heart failure develops oliguria, it could be due to worsening cardiac function leading to increased sympathetic drive and RAAS activation (cardiorenal syndrome), rather than a primary kidney issue. This requires diuretic management, not fluid administration.

How to Approach the Question

First, identify the keyword 'except'. This means you are looking for the option that does NOT fit the condition described in the stem.
The core concept is 'polyuria', which means excessive urine production (typically more than 3 liters per day).
Evaluate each option's effect on urine output.
Diabetes Insipidus is a classic cause of polyuria due to ADH deficiency.
Diabetes Mellitus causes polyuria through osmotic diuresis from high glucose.
Mannitol is an osmotic diuretic designed to cause polyuria.

Concept Tested & Keywords

Concept Tested: Regulation of urine output and causes of polyuria.
Stem keywords: polyuria, causes
Lead-in keywords: except
Negative lead-in flag: The question uses the word 'except', asking to identify the option that is NOT a cause of polyuria.

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E6 Medicine Harrison 22e Part 1 p. 384-386

E6 Medicine Harrison 22e Part 2 p. 921-923

Practise the full PGIMER NO - 2020

Attempt every question from this paper in a timed mock, then review the full solution for each one.