If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Advanced urinary system quiz


Clinical Application #1: Inulin and Measuring the Glomerular Filtration Rate

Inulin is a compound produced by plants such as artichokes, onions and garlic which does not get secreted nor reabsorbed along the nephron. Because of this special characteristic we can say that the amount of inulin excreted in the urine per minute is equal to the amount that is filtered by the glomerulus per minute (the glomerular filtration rate).
Doctors inject inulin directly into the blood plasma to determine the glomerular filtration rate. Two equations are utilized to determine the glomerular filtration rate. Remember, the inulin excreted per minute and inulin filtered per minute are equivalent to one another since no inulin gets secreted nor absorbed along the nephron.
End of reading passage.
Inulin excreted per minute=VU
  • Where V = rate of urine formation (mL/min)
  • Where U = inulin concentration in urine (mg/mL)
Inulin filtered per minute=GFRP
  • Where P = inulin concentration in plasma (mg/mL)
  • Where GFR = glomerular filtration rate (mL/min)
Based on the information above, determine the glomerular filtration rate of a patient with an inulin concentration in the urine of 15 mg per mL; an inulin concentration in the plasma of 0.25 mg per mL; and a rate of urine formation of 2 mL per minute.
The patient has a glomerular filtration rate of
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi