Cortisol (serum/plasma concentration)

Why Might This Test Be Ordered?

Your healthcare provider may recommend a cortisol test to diagnose or monitor conditions such as adrenal gland disorders (e.g., Cushing’s syndrome or Addison’s disease), evaluate stress responses, or check for hormonal imbalances. It can also help assess pituitary function or rule out other endocrine issues.

What to Expect During the Test

A blood sample will be drawn from a vein, usually in your arm. You may feel a slight pinch, but it typically doesn’t cause significant discomfort. The sample is then sent to a lab for analysis. No special preparation is usually needed, but your provider may advise fasting or timing the test around specific times of the day (e.g., morning for baseline levels).

Sample Collection and Preparation

Blood is the most common specimen for cortisol testing. If you’re taking medications that affect cortisol levels (e.g., steroids), inform your provider before the test. Some tests may require multiple samples at different times (e.g., early morning and late evening) to assess natural fluctuations.

What the Results Mean

Results are interpreted based on your clinical situation and may vary depending on whether the test was done as a single measurement or as part of a 24-hour urine collection (for cortisol metabolites). High or low cortisol levels can signal underlying health concerns, but your provider will discuss these findings with you in the context of your symptoms and medical history.