Cortisol Blood Test Name: What Is It Called? Guide

The cortisol blood test is most commonly called a serum cortisol test or plasma cortisol level. In medical settings, it may also be referred to as a cortisol AM/PM test, ACTH stimulation test (when combined with corticotropin), or simply a cortisol level check. This simple blood draw measures the amount of cortisol—a key stress hormone—circulating in your bloodstream and helps screen for adrenal disorders like Cushing’s syndrome or Addison’s disease. Today, updated reference ranges and circadian rhythm awareness make this test more precise than ever.

Why Cortisol Matters today

Cortisol regulates metabolism, immune response, and the sleep-wake cycle. Chronically high levels—often from stress, tumors, or steroid use—can lead to weight gain, high blood pressure, and osteoporosis. Low levels may cause fatigue, low blood pressure, and skin darkening. With rising awareness of adrenal fatigue and burnout, the serum cortisol test has become a standard part of preventive health panels offered by Lab Providers.

Common Names for the Cortisol Blood Test

Depending on the clinical context and sample type, healthcare providers may order the test under these names:

• Serum cortisol (most common – measures cortisol in blood serum)
• Plasma cortisol (similar to serum but uses plasma sample)
• AM cortisol (early morning draw, around 8 a.m., when cortisol peaks naturally)
• PM cortisol (late afternoon/evening draw to assess diurnal variation)
• 24-hour urinary free cortisol (UFC) (urine test for total daily cortisol output)
• Dexamethasone suppression test (DST) (follow-up after dexamethasone medication to check for Cushing’s)
• ACTH stimulation test (measures cortisol response to synthetic ACTH to evaluate adrenal function)
• Salivary cortisol (for convenient at-home collection, often used for late-night levels)

Quick Reference Table: Cortisol Test Types

Test Name	Sample Type	Typical Use
Serum Cortisol	Blood (serum)	General screening for adrenal disorders
AM/PM Cortisol	Blood (two draws)	Assess circadian rhythm
24-h Urinary Free Cortisol	Urine	Total daily production
Salivary Cortisol	Saliva	Cushing’s syndrome screening

How the Cortisol Blood Test Works (Update)

Today, most laboratories use high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) for cortisol measurement, offering greater accuracy than older immunoassays. Results are typically reported in micrograms per deciliter (µg/dL) or nanomoles per liter (nmol/L). Reference ranges have been refined to account for age, sex, and pregnancy—Lab Providers uses the latest guidelines from the Endocrine Society.

When Your Doctor Orders a Cortisol Test

Common reasons include symptoms of unexplained weight gain, high blood sugar, muscle weakness, fatigue, or abnormal body hair growth. For the most reliable results, your physician will likely request an early morning sample (7–9 a.m.) and possibly a second evening sample. Fasting is usually not required, but you may be asked to avoid strenuous exercise and stress the day before.

Interpreting Your Cortisol Results

A normal morning serum cortisol level generally ranges from 6 to 23 µg/dL (166 to 635 nmol/L), though exact values depend on the lab. Low cortisol may indicate adrenal insufficiency (Addison’s disease), while high levels could point to a pituitary tumor, adrenal tumor, or chronic stress. The current guidelines emphasize that a single reading is rarely diagnostic—suppression and stimulation tests are often needed.

Why Choose Lab Providers for Your Cortisol Test?

Lab Providers offers a full panel that includes AM and PM cortisol, urinary free cortisol, and the ACTH stimulation test. All testing is processed in CLIA-certified labs, with results available within 2–3 business days. Our patient portal provides clear, doctor-reviewed explanations of your numbers, helping you understand what your cortisol levels mean for your health—no confusing medical jargon.

Ready to take control of your adrenal health? Order your comprehensive cortisol blood test from Lab Providers today and get clarity on your stress hormone balance.

Order the Cortisol Blood Test Now →