ACTH stimulation test

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The ACTH stimulation test is a test procedure in endocrinology to check the function of the adrenal cortex . The test is used in humans, in veterinary medicine especially in dogs and horses. Here, blood is drawn from the patient and then 250 µg ACTH ( adrenocorticotropin ) are injected intravenously. In dogs, a dose of 5 µg / kg body mass is sufficient. Blood is drawn again after 30 minutes (humans) or 60 to 90 minutes (dogs). The test is primarily used to detect a hypofunction of the adrenal cortex . The cortisol content is determined in both blood samples . Since ACTH stimulates the production of cortisol in the adrenal cortex, the cortisol level increases in healthy people. In contrast, if the adrenal cortex is underactive, there is little or no increase in cortisol.

In dogs, a cortisol value below 2 µg / dl after stimulation is proof of an underactive adrenal cortex (Addison's disease), values ​​between 2.1 and 5 µg / dl are considered to be gray. It should be noted that previous doses of prednisolone derivatives can falsify the result, as they lead to a suppression of cortisol secretion. In dogs, the test is also used to control therapy when treating Cushing's syndrome with mitotane or trilostane . If Trilost is indicated, the test must be carried out four hours after the medication has been administered. The basal value should be below 1.3 µg / dl, the stimulation value below 7.3 µg / dl. In addition, the ACTH stimulation test is the only way to prove that a doctor has ( iatrogenic ) Cushing's syndrome. In this case, the cortisol starting value is low to normal and the stimulation value shows no or only a very small increase.

The ACTH stimulation test can also be used to diagnose disorders of steroid synthesis, in particular a 21-hydroxylase deficiency. Here the 17-OH- progesterone value is determined, which reacts excessively with a hydroxylase deficiency.

Individual evidence

  1. ↑ a b c d Internal medicine . Georg Thieme, Stuttgart 2001, ISBN 978-3-13-128751-9 , pp. 866 .
  2. ^ A b c Claudia E. Reusch: Primary hypoadrenocorticism in dogs (Addison's disease) . In: Small Animal Practice . tape 60 , no. 9 , 2015, p. 480-502 , doi : 10.2377 / 0023-2076-60-480 .
  3. ↑ Alex Gallagher: Demystifying Tests for Hyperadrenocorticism (website only accessible to registered professionals)