What is the Cushing’s test?
Cushing’s syndrome is a common metabolic disorder associated with disorders and changes in the cortisone metabolism. Cortisone is a so-called “stress hormone” which is involved in many metabolic processes of various organs in the body. An excess of cortisone in the body can trigger Cushing’s syndrome, which can be accompanied by a correspondingly large number of symptoms.
Cushing’s tests are essential to prove Cushing’s syndrome and thus an increase in cortisone levels, but also to differentiate the cause of the disease. Various organs are already involved in the regulation and production of the hormone, especially the pituitary gland and the adrenal cortex. Cushing’s tests can identify dysregulation and thus the origin of the disease by means of hormone precursors and reactions of the body. Various different tests are available for this purpose. First of all, there is the so-called “dexamethasone screening test”, which can be carried out on both humans and animals.
What are the indications for the test?
The primary Cushing’s test is carried out if there is a suspicion of Cushing’s syndrome, i.e. an increased presence of cortisone. Cushing’s syndrome can manifest itself with numerous symptoms. Typical are redistributions of fatty tissue with a moon face, a bull’s neck and a so-called “trunk obesity“, i.e. a male type of fat distribution.
In addition, the hormonal changes can lead to high blood pressure, skin bleeding, osteoporosis and muscle atrophy. It is not uncommon for psychological changes to occur, for example in the form of particular euphoria or with depressive symptoms. During development, there may also be short stature, infertility, small testicles and cycle disorders.
These are all typical symptoms of Cushing’s syndrome, which in combination provide a strong suspicion of Cushing’s syndrome and are indications for Cushing tests. Different tests lead to different results. If the primary dexamethasone test gives a positive result, further tests are indicated to differentiate the exact causes of Cushing’s syndrome.
Procedure of the test
The dexamethasone screening test, which precedes further Cushing’s tests, is performed by the single nightly administration of dexamethasone. This is an artificial drug similar to cortisone. This single administration suppresses the further production of cortisone in healthy people via a counter-regulation.
If the cortisone level in the blood in the morning is not the same as the previous day, a Cushing’s syndrome has been proven. This is due to the fact that the regulatory mechanisms no longer function due to the pathological excess of cortisone and the level thus remains elevated despite nightly dexamethasone administration. The exact reason for the Cushing’s syndrome has not been determined, however, so that further hormone level determinations and tests are necessary. The levels of the various regulatory hormones of the organs can be determined for this purpose. In most cases, the determination of the hormones “ACTH” and “CRH” already provide information about the causative organ.
