Cortisol (Morning)

What is morning cortisol?

Cortisol is a vital glucocorticoid hormone produced by the adrenal glands, which sit on top of the kidneys. It helps maintain blood sugar during fasting, sustain blood pressure and keep inflammatory responses in balance. In situations such as illness, surgery or intense stress, its secretion increases, enabling the body to cope with these challenges. Because of these vital functions, both too little and too much cortisol can lead to different health problems.

Cortisol production is controlled by a regulatory chain linking the hypothalamus, the pituitary gland and the adrenal glands; ACTH, secreted by the pituitary, is the key to this chain. The hormone's blood level peaks in the early morning hours, so a blood sample taken in the morning provides the most information about the production capacity of the adrenal glands. The test is performed on serum using an immunoassay, and the result is reported in µg/dL.

When is a morning cortisol test ordered?

Your doctor most often orders morning cortisol when they suspect that the adrenal glands are not producing enough hormone. A low result at the time of day when cortisol should be at its highest is a meaningful clue in this respect. When cortisol excess is suspected, the result is evaluated together with evening cortisol and suppression tests.

• Long-lasting weakness, tiring easily and unexplained weight loss
• Low blood pressure, dizziness on standing up and craving for salty foods
• Darkening of the skin and gums
• Assessing adrenal function after long-term corticosteroid therapy is stopped
• Monitoring in pituitary gland disease or after pituitary surgery
• Symptoms suggesting cortisol excess (suspected Cushing's syndrome)

How do I prepare for a morning cortisol test?

For morning cortisol, blood is usually drawn between 7:00 and 10:00 a.m., most often around 8:00 a.m.; since the result is interpreted according to this time window, it is important not to be late. Fasting is not mandatory, but if tests that require fasting have also been ordered, you will need to give blood after an overnight fast. You are advised to sleep as usual the night before and to rest calmly, without rushing around, before giving blood. Because the time since waking up can also affect the result, it helps to wake up at your usual time on the morning of the test.

Corticosteroid medications in the form of tablets, injections, creams, eye drops, nasal sprays or inhalers can affect the measurement and suppress the body's own cortisol production. Birth control pills and estrogen-containing treatments can increase the protein that carries cortisol, making values appear higher than they actually are. Do not stop these medications without consulting your doctor, but mention them when the sample is taken; also mention any high-dose biotin supplements. Because a Curavita nurse can draw your blood at your home, you do not need to set off early to make it within this short morning window.

What does a morning cortisol result mean?

A markedly low morning cortisol suggests that the adrenal glands cannot produce enough hormone. This can be seen in Addison's disease, which originates in the gland itself, in insufficient ACTH secretion from the pituitary, or when the glands are suppressed after long-term corticosteroid use. For borderline low values, your doctor may order additional tests, such as the ACTH stimulation test, to clarify the diagnosis.

A high morning cortisol, on the other hand, is often related to stress, acute illness, lack of sleep, pregnancy or estrogen-containing medications. On its own it does not indicate Cushing's syndrome, because morning values can remain within normal limits in this disease. Reference ranges vary with the time the blood was drawn, the method used, the laboratory, age and sex; the morning range of the laboratory performing the test is given on this page. For your morning cortisol result to be interpreted correctly, your doctor needs to consider your symptoms and your other tests together.