Blood draw
ACTH
ACTH; adrenal axis/pituitary
€ 59,00
All tests
Hormones · Blood
ACTH
Pituitary hormone that prompts the adrenal glands to make cortisol; can only be interpreted together with a cortisol value.
At a glance
- Measured in blood
- In 1 test panel
- Check the preparation
Explanation
ACTH: what is measured?
ACTH (adrenocorticotropic hormone) is made in the pituitary gland, a hormone gland below the brain. It prompts the adrenal glands to make cortisol. Normally, ACTH rises when there is too little cortisol and falls when there is too much. Like cortisol, ACTH has a daily rhythm: it is highest early in the morning and lowest at night.
What can it detect?
- Where the cause lies when cortisol is too low: in the adrenal gland itself (Addison's disease, with a high ACTH) or in the pituitary gland (with a low ACTH)
- Where the cause lies when cortisol is too high: an ACTH-producing tumor, usually a benign tumor of the pituitary gland (Cushing's disease), or the adrenal gland itself
- Suppression of the pituitary and adrenal glands by the use of corticosteroids
Result
What does the result mean?
ACTH too high
A raised ACTH is often temporary: early in the morning and with stress, pain or illness, the value is higher. Together with a low cortisol, a high ACTH points to a deficiency caused by the adrenal glands themselves (Addison's disease), with symptoms such as severe tiredness, weight loss, salt craving, low blood pressure, nausea and darkening skin. Together with a high cortisol, a high ACTH may fit Cushing's disease, usually due to a benign tumor of the pituitary gland. Rarely: a tumor outside the pituitary gland makes ACTH. Without a cortisol value from the same sample, a raised ACTH cannot be interpreted.
ACTH too low
In the evening and at night, a low ACTH is normal. During the day, the use of corticosteroids (tablets, inhalers, nasal spray, skin cream or injection) is the most common cause of a low ACTH: these medicines suppress the pituitary gland. Together with a low cortisol, a low ACTH may point to reduced function of the pituitary gland, for example after surgery or radiotherapy or due to a pituitary tumor, with symptoms such as tiredness, dizziness, nausea, abdominal pain and weight loss. Together with a high cortisol, a low ACTH fits an adrenal gland that itself makes too much cortisol.
After an abnormal result
The GP assesses ACTH together with a cortisol value from early in the morning and asks about the use of corticosteroids. With a low cortisol and a high or, on the contrary, low ACTH, referral follows to an endocrinologist (internist specializing in hormones), usually for a stimulation test. With a high cortisol and matching symptoms, tests that confirm the excess come first, followed by imaging of the pituitary or adrenal glands.
Reliability
How reliable is the test?
ACTH is not a screening test: the value can only be assessed together with a cortisol value from the same moment. The Dutch Society for Clinical Chemistry (NVKC) calls the interpretation of ACTH and cortisol results complex, because both hormones vary strongly over the day. ACTH is mainly meaningful after a too high or too low cortisol has been found: the value then shows where the cause lies. In people without symptoms, a single ACTH value says little, and the value says nothing about stress or 'adrenal fatigue'.
What can affect the result?
- Timing: ACTH is highest early in the morning; only a sample taken at a fixed time can be compared with the reference values.
- The sample must be cooled and processed quickly; ACTH breaks down quickly in blood, which can give a result that is too low.
- Corticosteroids in any form lower ACTH; stress around the sample collection, pain and illness raise it temporarily.
- Reference values differ per laboratory and measurement method; biotin supplements can interfere with some measurement methods.
Preparation
- Have your blood taken between 8.00 and 10.00, because ACTH drops during the day.
- Avoid stress and heavy exercise shortly before the sample is taken.
Who it is for
Who is the test useful for?
Useful for
Useful if a too low or too high cortisol has been found or is strongly suspected, to determine whether the cause lies in the pituitary gland or in the adrenal gland, and in people with a known pituitary disorder. As a stand-alone test, without cortisol from the same sample, ACTH has little value. Not useful with tiredness or stress without other symptoms: the result is then almost always normal or cannot be interpreted.
How common is it?
Adrenal and pituitary disorders are rare. Addison's disease is estimated to occur in 40 to 115 per million inhabitants, and Cushing's syndrome due to a tumor is diagnosed in about 50 people a year in the Netherlands. Much more often, an abnormal ACTH is the result of using corticosteroids.
GP brochure on adrenal diseases (Dutch adrenal patient association NVACP) and Maastricht UMC+, Department of Endocrinology
Drawbacks and risks
- An abnormal value due to the timing, stress or a sample that was not stored properly can cause unnecessary worry about the pituitary or adrenal glands and unnecessary follow-up testing.
- A single ACTH result without a cortisol value cannot be interpreted and can wrongly reassure or alarm.
Get tested
ACTH: test panels
ACTH is part of these test panels. You order online and have your blood drawn at a collection point or collect the sample at home.
Evidence
Sources
This explanation is based on Dutch guidelines and independent information. It is general information, not a diagnosis. Discuss an abnormal result with your GP.
More about risks and results