Cortisol, Serum (24-Hour Urinary Free Cortisol)

Why This Test Is Done

Your doctor may order this test if they suspect conditions like Cushing’s syndrome (too much cortisol), adrenal insufficiency (too little cortisol), or to monitor treatment for hormone-related disorders. It’s also used in research or specialized evaluations where daily cortisol patterns are important.

What to Expect Before the Test

You’ll collect all urine for a full 24-hour period, typically starting after midnight of one day and ending just before midnight the next. Store samples in a refrigerator until you bring them to the lab. Follow your doctor’s instructions precisely to ensure accurate results.

How the Test Works

Urine is tested for cortisol levels using a chemical method that detects the hormone’s presence. The test measures how much cortisol is excreted naturally in your urine over time, rather than measuring cortisol directly in your blood.

Possible Results and Interpretation

Results are compared to standard ranges for healthy adults, though exact values can vary by lab. High levels may indicate Cushing’s syndrome or other causes of excess cortisol, while low levels could signal adrenal problems or other conditions affecting hormone balance.