Hormone testing: frequently asked questions

A hormone blood test measures the concentration of a specific hormone in a sample of your blood. Clinicians use the result, together with your symptoms and history, to assess how part of the endocrine system is working.

It depends on the test. Some hormone tests are unaffected by food, while related metabolic tests may require fasting. Always follow the specific instructions from the clinician or laboratory that ordered the test. See our guide to preparing for a hormone test.

For some hormones, yes. Cortisol and testosterone, for example, follow a daily rhythm, so the time of the blood draw is recorded and affects interpretation. Your clinician may ask for a morning sample.

Reference ranges are set by each laboratory based on the equipment and methods it uses, so they can differ. Interpret your result against the range printed on your own report. Our guide to reference ranges explains why.

You can learn what a test measures and what the terms mean, but a valid interpretation considers your full clinical picture. Only a qualified clinician can interpret your results in context.

There is no single answer; testing frequency depends on the hormone, your symptoms, any condition being monitored, and your clinician's judgment. Routine testing without a reason is not generally recommended.