Cortisol (24-hour urinary free cortisol)

Why This Test Is Done

Your doctor may order a 24-hour urine cortisol test if they suspect conditions like Cushing’s syndrome (too much cortisol) or adrenal insufficiency (too little cortisol). It’s also used to monitor treatment effectiveness for these conditions or other hormonal imbalances. Unlike blood tests, this method captures cortisol levels throughout your entire day, providing a more complete picture.

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. Keep the collection container clean and refrigerate it if needed. Avoid certain medications (like some pain relievers or steroids) that could affect results, so check with your doctor beforehand.

What Happens During the Test

After collecting your urine sample, it will be sent to a lab for analysis. The lab measures cortisol concentration in your urine, which reflects how much cortisol your body produced over the day. No special preparation is needed beyond following the collection instructions.

What the Results Mean

Results are compared to standard ranges for healthy adults. High levels may suggest Cushing’s syndrome or other hypercortisolism conditions, while low levels could indicate adrenal insufficiency or other causes of hypocortisolism. Your doctor will interpret results in the context of your symptoms and medical history.