Question

The amount of urea reabsorbed in the urinary tubules is
a) 5gm
b) 17gm
c) 21gm
d) 20gm

Answer 1

Approximately 50 gm of urea is filtered everyday, of which around 25–40 gm is excreted with the urine.

The re-absorption of urea that takes place in the proximal tubule, collecting ducts and active secretion of urea (Henle loop) all leads to circulation between nephron lumen and renal medulla.

Approximately 50% of urea is reabsorbed with the re-absorption of water. Therefore, the answer is “C” 21 gm