Question:medium
A plasma urea to creatinine ratio of 20:1 may be seen in:
A plasma urea to creatinine ratio of 20:1 may be seen in:
Show Hint
A wide urea to creatinine gap means urea is being reabsorbed, the signature of underperfusion.
Updated On: Jun 24, 2026
- Rhabdomyolysis
- Ureteric calculi
- Pre-renal failure
- Chronic glomerulonephritis
Show Solution
The Correct Option is C
Solution and Explanation
The key number is the ratio. Normal blood urea sits about ten to fifteen times the creatinine. A value near 20:1 is the textbook signal of a pre-renal state.
Think about the physiology. When the kidney is poorly perfused, as in volume loss or low cardiac output, the tubules slow down the urine and pull back sodium, water, and urea. Creatinine slips through because tubules do not reabsorb it. So urea climbs faster than creatinine and the ratio widens. That is pre-renal failure, option C.
Run the distractors. In rhabdomyolysis muscle breakdown floods the blood with creatinine, dragging the ratio down rather than up, so option A is out. Ureteric stones block outflow; this back pressure raises urea and creatinine in step, so the ratio stays ordinary and option B fails. Chronic glomerulonephritis damages the filtering units themselves, again raising both markers together and keeping a normal ratio, so option D fails.
Only an underperfused kidney selectively spares urea reabsorption and gives the wide 20:1 gap.
\[\boxed{\text{Pre-renal failure}}\]
Think about the physiology. When the kidney is poorly perfused, as in volume loss or low cardiac output, the tubules slow down the urine and pull back sodium, water, and urea. Creatinine slips through because tubules do not reabsorb it. So urea climbs faster than creatinine and the ratio widens. That is pre-renal failure, option C.
Run the distractors. In rhabdomyolysis muscle breakdown floods the blood with creatinine, dragging the ratio down rather than up, so option A is out. Ureteric stones block outflow; this back pressure raises urea and creatinine in step, so the ratio stays ordinary and option B fails. Chronic glomerulonephritis damages the filtering units themselves, again raising both markers together and keeping a normal ratio, so option D fails.
Only an underperfused kidney selectively spares urea reabsorption and gives the wide 20:1 gap.
\[\boxed{\text{Pre-renal failure}}\]
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