Hormones
ACTH (Adrenocorticotropic Hormone)
Hormones
ACTH is made in the pituitary gland and stimulates the adrenal glands to produce cortisol. It is measured alongside cortisol to work out where in the chain a problem lies.
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The pituitary releases ACTH, which tells the adrenal glands to make cortisol. When cortisol rises, ACTH is suppressed, and vice versa. Measuring both from the same sample shows whether a problem sits in the adrenal glands or in the pituitary. ACTH varies considerably across the day and is highest in the early morning.
The test is used when adrenal insufficiency (Addison's disease) is suspected, and when investigating excess cortisol (Cushing's syndrome). It is always taken together with cortisol and interpreted by a doctor, often as part of a wider assessment that includes stimulation testing.
What a high value can mean
A high ACTH with a low cortisol indicates primary adrenal insufficiency, meaning the adrenal glands are not responding. A high ACTH with a high cortisol is seen with ACTH-producing tumours, most often in the pituitary. Severe stress and acute illness also raise ACTH temporarily.
What a low value can mean
A low ACTH with a low cortisol indicates the pituitary is not signalling as it should, for example after prolonged corticosteroid treatment or with disease of the pituitary. A low ACTH with a high cortisol indicates the adrenal glands are producing too much on their own.
The test is taken in the morning, usually between 07:00 and 09:00, because the level varies across the day. The sample is fragile and must be chilled and handled quickly, so call the sampling location in advance. Never stop corticosteroid treatment before a test without speaking to your doctor. Bring valid ID.
Order your test
Choose your test and pay online. Your lab referral is created straight away.
Give your sample
Visit any of our partner sampling locations. No appointment needed at most of them.
The lab analyses it
Your sample is analysed at an accredited Swedish laboratory.
Get your results
Your values appear in your account with reference ranges and an explanation of each marker.
In the morning, usually between 07:00 and 09:00, when the level is highest. A sample taken later in the day is difficult to interpret.
No, fasting is not normally required. The time of day matters, as does being rested and calm at the appointment.
Yes. Acute physical or psychological stress, illness and lack of sleep raise ACTH temporarily. The value is therefore always interpreted alongside cortisol and your circumstances.