What Can a Urine Cortisol/Creatinine Test Tell Us?

Q:
What Can a Urine Cortisol/Creatinine Test Tell Us?

A:
It is a widespread and sensitive way to diagnose hypercortisolism by measuring urinary cortisol excretion. It is critical to collect 24-hour general index, since cortisol is produced in discrete pulses, which leads to plasma concentrations rising and falling at intervals.

Important Tips for Urine Cortisol Test:

  • Cortisol excretion of people with moderate renal impairment (creatinine clearance (Ccr) less than 60 mL/min) and severe renal impairment (Ccr less than 20 mL/min) have declined continually.
  • The collection of urine samples for more than or less than 24 hours can also bias test results. Therefore, when measuring cortisol excretion, the creatinine excretion rate must be measured simultaneously. If the excretion rate of creatinine is relatively constant and the individual difference is small during 24 hours, urinary albumin excretion rate can be calculated based on the ratio of urinary protein to urinary creatinine in random sampling.
  • Fluid intake wouldn’t affect creatinine excretion but cortisol excretion.
  • In adults under the age of 50, the daily creatinine excretion of men should be 20-25 mg per kilogram of lean body weight, and the daily creatinine excretion of women should be 15-20 mg per kilogram of lean body weight.
  • In adults between the age of 50 to 90, creatinine excretion gradually decreased by 50% (male dropped to about 10 mg/kg), mainly due to the decrease in muscle mass. However, excretion of cortisol and its metabolites varies during the day, but creatinine excretion does not. Therefore, urine collection test results cannot be corrected based on creatinine levels.

In any case though, please go see a doctor for professional help.

 

Key words: Urine Cortisol/Creatinine Test; hypercortisolism; urinary cortisol excretion; creatinine clearance; urinary protein.

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.