The stimulation test | ACTH

The stimulation test

In the stimulation test, the doctor tries to find out whether there is a so-called primary adrenal cortex hypofunction. The test is carried out on an empty patient and the patient should lie quietly in bed during the test. First of all, the cortisol level is determined in the patient.

Then an artificially produced ACTH is injected directly into the blood via a venous access. The doctor simulates an increased release of ACTH and orders the adrenal cortex to release more cortisol. A healthy adrenal gland would then release cortisol as expected.

After half an hour and a whole hour, samples are taken again and the cortisol level is determined. If there is no increase, a primary adrenal insufficiency or a secondary adrenal insufficiency that has existed for some time can be assumed. The test can lead to hypersensitivity reactions and cause skin reactions, dizziness, nausea, vomiting and itching.

In case of acute allergic shock, countermeasures must be taken directly. Find out more about the topics here:

  • Primary adrenocortical insufficiency
  • Secondary adrenocortical insufficiency

Normal values for laboratory values are always only statistically determined values. A slight deviation therefore does not necessarily have to have a disease value.

Since ACTH is subject to a circadian rhythm, the values vary depending on the time of day. Between eight and ten o’clock the normal value is between 10 and 60pg/ml. In the evening around 9 pm the value is between 3 and 30pg/ml. In the stimulation test, the value should increase by at least 70pg/ml or rise to at least 200pg/ml.

The consequences of ACTH deficiency

ACTH deficiency can be caused by hypofunction of the pituitary gland or hypothalamus. The consequence is a likewise reduced cortisol level. Those affected accordingly suffer from the consequences of cortisol deficiency.

These include fatigue, lack of energy and weight loss, and even anorexia. Muscle and joint pains are also described by those affected. Fever and anemia may occur.

Children in particular often suffer from hypoglycaemia due to the lack of cortisol. In many cases there is also low blood pressure, which drops further when the patient suddenly changes position. Women often suffer from dry, itchy skin and loss of pubic hair.

The skin of those affected appears alabaster-coloured. The combination of these symptoms is also called Addison’s disease. An Addison’s disease crisis can also be triggered when people take cortisol permanently and suddenly stop taking it.

The symptoms may be slightly altered in patients with primary hypothyroidism. In this case, however, the ACTH values are within the normal range and only the cortisol level is reduced. .

The consequences of an increase in ACTH

An increased ACTH release leads to an increased cortisol release. This in turn triggers Cushing’s disease. The cause of increased ACTH production is often a tumour in the area of the pituitary gland.

Those affected suffer from a changed fat distribution. While the limbs become thinner, those affected gain weight on the trunk and head. This is also called trunk obesity.

The neck raises a fat fold called the buffalo neck and the face becomes roundish. The skin becomes thinner and more sensitive, resulting in increased stretch marks, haematomas and acne. Adults develop osteoporosis and children show weak growth.

High blood pressure and atherosclerosis (calcification of the vessels), as well as oedema are also typical. Affected persons develop diabetes mellitus as a secondary consequence, as glucose tolerance decreases. In some cases there is a loss of libido and a lack of menstrual bleeding.

Those affected are also quickly irritable and can also develop depression. In severe cases, paranoid psychosis also occurs. Due to the immunosuppressive effect of cortisol, affected persons are very susceptible to infections. The probability of deep vein thrombosis and pulmonary embolism also increases. You can find more information about Cushing’s disease here.