Urine Concentration & Dilution — Renal Physiology

Urine Concentration & Dilution MCQs: practice questions

Sample Urine Concentration & Dilution multiple-choice questions from Renal Physiology.

1. Isosmotic urine has a free-water clearance of:

   • A. Negative
   • B. Positive
   • C. Zero
   • D. Infinite
   • E. Equal to GFR

2. During high water intake, the final urine is produced with:

   • A. An osmolarity fixed at 1,200 mOsm/L
   • B. High osmolarity and negative free-water clearance
   • C. High osmolarity and positive free-water clearance
   • D. Zero urine flow and negative clearance
   • E. Low osmolarity and positive free-water clearance

3. In the absence of ADH, the final urine osmolarity can fall to approximately:

   • A. 2,000 mOsm/L
   • B. 300 mOsm/L
   • C. 600 mOsm/L
   • D. 1,200 mOsm/L
   • E. 50 mOsm/L

4. Both forms of diabetes insipidus produce:

   • A. High-volume dilute urine
   • B. Low-volume concentrated urine
   • C. Hyperosmotic urine
   • D. Negative free-water clearance
   • E. Decreased plasma osmolarity from water retention

5. Urea contributes to the medullary osmotic gradient through:

   • A. Complete proximal secretion
   • B. Recycling from the inner medullary collecting duct
   • C. Glomerular protein filtration
   • D. Reabsorption in the renal pelvis
   • E. Excretion without reabsorption

6. Nephrogenic diabetes insipidus is characterized by:

7. Loop diuretics also impair urine dilution because they:

8. Central diabetes insipidus is caused by:

9. Negative free-water clearance indicates:

10. During water deprivation, ADH secretion:

11. The thick ascending limb contributes to urine concentration by:

12. Drinking a large amount of water suppresses:

13. SIADH is characterized by:

14. ADH increases water permeability in the collecting duct by acting through:

15. Low ADH produces urine that is:

16. Positive free-water clearance indicates:

17. In SIADH, free-water clearance is:

18. In the absence of ADH, the late distal tubule and collecting duct are relatively:

19. Water deprivation causes urine volume to:

20. A loop diuretic impairs urine concentration by:

21. The corticopapillary gradient is established primarily by:

22. ADH increases the size of the corticopapillary gradient by stimulating:

23. The proximal tubule reabsorbs water:

24. High ADH produces urine that is:

25. Urine Concentration & Dilution 30 questions • Five related options • One best answer • Explanation 1. The corticopapillary osmotic gradient extends from approximately:

26. The vasa recta maintain the medullary gradient by:

27. The maximum urine osmolarity described in BRS is approximately:

28. Free-water clearance is calculated as:

29. Water deprivation causes urine osmolarity to:

30. In primary polydipsia, urine is typically: