Cortisol is your body's main stress hormone, made by the adrenal glands sitting on top of each kidney. Because it follows a strong daily (circadian) rhythm that peaks in the early morning, a cortisol blood test is almost always drawn between about 7 and 9 AM, when a normal result is roughly 6-23 µg/dL. A morning value inside that band is considered normal; results well above or below it can point to problems with the adrenal or pituitary glands.
What is a cortisol test?
Cortisol is a steroid hormone that helps you respond to stress, keeps blood sugar and blood pressure steady, regulates metabolism, and dampens inflammation. Its release is controlled by a feedback loop: the brain's hypothalamus and pituitary gland signal the adrenal glands (via ACTH) to make cortisol, and rising cortisol then switches that signal back off. This is why cortisol is often measured alongside ACTH when a doctor is trying to locate the source of a problem.
A doctor may order a morning cortisol test if you have symptoms that suggest too much cortisol (unexplained weight gain around the trunk and face, easy bruising, purple stretch marks, high blood pressure, muscle weakness) or too little (fatigue, weight loss, low blood pressure, darkening of the skin, salt craving). It is also used to monitor people on long-term steroid medicines and to investigate unexplained low sodium or low blood sugar. Cortisol can be measured in blood, saliva or a 24-hour urine collection; this article focuses on the standard morning blood test, reported in µg/dL as used by most Indian laboratories.
Cortisol normal range
For a blood sample drawn in the early morning, a normal morning cortisol level sits in the range of about 6-23 µg/dL. Because levels fall through the day to a low point around midnight, the same number that is normal at 8 AM would be unexpectedly high at night. That is exactly why the collection time is written on your report and why you should not compare a morning value against an evening one. The bands below show how ExaHealth groups a morning result from low to high. Treat these as a guide for conversation with your doctor, not a diagnosis on their own.
| Morning cortisol (µg/dL) | Interpretation band |
|---|---|
| 0-1 | Critically low |
| 2-3 | Severely low |
| 4-5 | Moderately low |
| 5.1-5.9 | Borderline low |
| 6-23 | Normal |
| 24-28 | Borderline high |
| 29-35 | Moderately high |
| 36-50 | Severely high |
| 51-100 | Critically high |
Reference ranges vary slightly between laboratories depending on the assay used, so always read your value against the range printed on your own report. Cortisol is a hormone that is easiest to understand over time rather than from a single reading; tracking your results and their collection times in one place with ExaHealth makes it easier to see a real trend and to share it with your doctor.
Normal range by age, sex and condition
The morning reference band above is the single, general adult range attached to this test; the ExaHealth database does not hold separate numeric bands for different ages, sexes or conditions. Rather than invent group-specific cut-offs, it is more useful to understand the real-world factors that shift a cortisol result and why timing and context matter so much when your doctor interprets it.
| Situation | How it affects interpretation |
|---|---|
| Time of day | Cortisol is highest in the early morning and lowest near midnight. A number is only meaningful next to the time it was drawn, which is why the morning slot is standard. |
| Acute stress or illness | Pain, infection, surgery, or even anxiety about the blood draw can genuinely raise cortisol. A high value during acute illness is often an appropriate stress response, not disease. |
| Pregnancy and oestrogen | Pregnancy and oestrogen-containing pills raise the carrier protein that binds cortisol, so total blood cortisol can read higher even when the active hormone is normal. |
| Steroid medicines | Inhaled, oral, or injected corticosteroids suppress the body's own cortisol and can cause a low morning result. Some steroids also cross-react with the assay. Always tell the lab and your doctor about steroid use. |
| Shift work and sleep | Night shifts and disturbed sleep shift the natural rhythm, so the expected morning peak may not line up with clock time. |
| Older age | The overall rhythm tends to flatten with age, but the morning reference band is still applied; interpretation leans more on symptoms and follow-up testing. |
Because so many everyday factors move the number, a single abnormal cortisol is rarely the final answer. Doctors usually confirm with repeat or dynamic testing (such as ACTH stimulation or dexamethasone suppression) before diagnosing a disorder. Cortisol also sits within a wider hormone picture, so it is often read alongside related markers such as DHEA-S and, in the broader context of women's hormone health.
What high cortisol means
On a morning test, a value above the normal band (from the borderline-high zone of 24-28 µg/dL upward, and clearly abnormal in the moderate-to-critical bands of 29 µg/dL and beyond) suggests the body is exposed to too much cortisol. The most common everyday cause is ordinary stress or acute illness, which raises cortisol temporarily and appropriately. Persistently high cortisol, however, can reflect Cushing's syndrome — a state of chronic cortisol excess caused by a pituitary tumour producing too much ACTH, an adrenal tumour, or, most commonly, long-term steroid medication.
Typical features of sustained cortisol excess include weight gain concentrated on the trunk and face (sometimes called a rounded or "moon" face), a fatty pad at the upper back, thin skin that bruises easily, purple stretch marks, high blood pressure, raised blood sugar, muscle weakness, mood changes and, in women, irregular periods or extra facial hair. Because a single high morning value can simply reflect stress, doctors confirm suspected Cushing's with additional tests — commonly a late-night salivary cortisol, a 24-hour urine cortisol, or an overnight dexamethasone suppression test — before making a diagnosis.
What low cortisol means
A low morning cortisol — falling into the borderline-low band (5.1-5.9 µg/dL) and, more concerningly, the moderate, severe or critical low bands below that — means the adrenal glands may not be making enough hormone. This is called adrenal insufficiency. When the adrenal glands themselves are damaged (often by an autoimmune process) it is known as Addison's disease (primary adrenal insufficiency); when the pituitary gland fails to send enough ACTH signal, it is called secondary adrenal insufficiency. A very common cause of low cortisol is suddenly stopping long-term steroid medication, which leaves the body's own production suppressed.
Symptoms tend to come on slowly and can be vague: ongoing tiredness, loss of appetite, weight loss, low blood pressure with dizziness on standing, salt craving, nausea, and in Addison's disease a characteristic darkening of the skin. A critically low cortisol (in the lowest bands) can signal an adrenal crisis — a medical emergency with severe weakness, vomiting, low blood pressure and confusion that needs immediate hospital care. If you take steroids and feel severely unwell, especially during another illness, seek urgent medical attention. A low morning value is usually confirmed with an ACTH stimulation test before a diagnosis is made.
How to manage and support healthy cortisol
Genuine cortisol disorders such as Cushing's or Addison's need medical diagnosis and treatment — they cannot be fixed with lifestyle alone, and you should never start or stop steroid medicines without your doctor's guidance. That said, everyday cortisol swings driven by stress and poor sleep are things you can influence:
- Protect your sleep. Cortisol's rhythm is tied to your sleep-wake cycle. A regular bedtime and 7-8 hours of sleep help keep the natural morning peak and night-time dip in order.
- Manage stress actively. Practices with good evidence for calming the stress response — yoga, pranayama and breathing exercises, meditation, and regular walking — are widely available and culturally familiar across India.
- Move, but don't overtrain. Regular moderate activity supports a healthy stress response, while chronic over-exercising without recovery can keep cortisol elevated.
- Eat balanced, regular meals. A steady eating pattern built around whole grains, dals and legumes, vegetables, fruit and adequate protein helps keep blood sugar stable and avoids the stress of long fasts. Go easy on excess caffeine, which can nudge cortisol up.
- Limit alcohol and don't smoke. Both disturb sleep and the stress-hormone system.
When to see a doctor: book a review if you have persistent unexplained weight gain with easy bruising and stretch marks, or ongoing fatigue with weight loss, dizziness on standing and skin darkening — and seek urgent care for the severe-crisis symptoms described above. Your doctor may order a morning cortisol together with ACTH and confirmatory tests. If you are already tracking hormone health, it can help to view cortisol alongside markers such as testosterone and prolactin, and to keep the full record in the lab tests library.
Guidelines and references
The interpretation bands in this article come from ExaHealth's biomarker reference database, applied to a standard early-morning blood sample reported in µg/dL. There is no single external guideline year attached to these bands; they reflect widely used standard laboratory reference ranges, which vary modestly between labs and assays.
- Standard laboratory reference ranges for morning serum cortisol (read against the range on your own report).
- Endocrine Society — professional body for hormone and adrenal disorders.
Frequently asked questions
What is a normal cortisol level in the morning?
For blood drawn in the early morning, a normal morning cortisol is roughly 6-23 µg/dL. Always compare your result against the reference range printed on your own report, as ranges vary between labs.
Why does cortisol have to be measured in the morning?
Cortisol follows a strong daily rhythm, peaking in the early morning and falling to its lowest around midnight. Testing in the morning captures the expected peak, so the same number is only meaningful next to the time the blood was drawn.
What does a high cortisol level mean?
A high morning cortisol most often reflects ordinary stress or acute illness. When it stays high, it can point to Cushing's syndrome or long-term steroid use, and doctors confirm this with additional tests before diagnosing.
What does a low cortisol level mean?
A low morning cortisol suggests the adrenal glands may not make enough hormone — a condition called adrenal insufficiency, including Addison's disease. A common cause is suddenly stopping long-term steroid medicine.
Can stress raise my cortisol test result?
Yes. Acute stress, pain, infection or even anxiety about the blood draw can genuinely raise cortisol. This is why a single high value is usually rechecked or confirmed with further testing before any diagnosis.
Do I need to fast before a cortisol test?
A cortisol blood test does not usually require fasting, but the timing (early morning) matters most. Follow your lab's instructions and tell them about any steroid medicines, as these can affect the result.