24-Hour Urinary Free Cortisol (Total Cortisol Excretion)

This urine test helps your healthcare provider evaluate how well your kidneys are working and look for signs of infection, dehydration, or other conditions that may need further evaluation or treatment.

Your healthcare provider may order this test if you have symptoms like unexplained weight gain, high blood pressure, fatigue, or mood changes that could be linked to abnormal cortisol levels. It’s also used to evaluate conditions like Cushing’s syndrome (too much cortisol) or adrenal insufficiency (too little cortisol).

During the test, your urine is collected over a set period of time and sent to a laboratory, where specialists measure the substances it contains so your care team can use the results to guide your diagnosis and treatment plan.

You’ll collect your urine for 24 hours, starting and ending at the same time each day. The sample is typically sent to a lab for analysis to measure total cortisol excreted. This method provides a more accurate picture of your daily cortisol production than single blood tests.

You will be given a clean collection container and asked to collect your urine at home following the exact schedule your provider gives you. Store the container in a cool place or refrigerator as instructed, and return it to the lab by the deadline you were given.

Follow your provider’s instructions carefully. Typically, you’ll collect all urine for a full 24-hour period in a special container. Empty your bladder before starting and discard the first urine sample. Store the remaining urine in a cool place until you return it to the lab. Do not miss any urine or add extra water to dilute it.

Before the test, your provider will explain the collection schedule, review your current medications, and tell you whether you need to drink more or less water. The test itself is painless, since no needles or blood samples are required.

No special preparation is usually needed, but avoid taking certain medications that may affect cortisol levels (like some steroids) unless your provider instructs otherwise. If you’re pregnant, breastfeeding, or have recent stress or illness, let your provider know.