Hormones can be determined in the blood and urine. The 24-hour urine collection is generally used for the urine test. In many cases, disorders in metabolic processes cannot be detected by measuring hormone levels alone. Suppression (inhibition) or stimulation tests are therefore often necessary to diagnose hormone excess or hormone deficiency. Most tests can be carried out under both outpatient and inpatient conditions, but some can only be carried out under inpatient conditions. Please note that outpatient functional tests can take up to 5 hours and you will usually have to come to the examination on an empty stomach. Our outpatient team will be happy to provide you with more information about your personal appointment schedule. We carry out the outpatient tests in our gastroenterological functional laboratory. The inpatient tests are carried out on our endocrinology ward M2A (level 2, lifts C).

The ACTH test is particularly suitable for assessing adrenal cortical function. Physiologically, stimulation with ACTH leads to an increase in cortisol in the blood. This test is clinically important for clarifying suspected adrenal cortical insufficiency (Addison's disease or iatrogenic after corticosteroid therapy), as an alternative to the insulin hypoglycaemia test in suspected anterior pituitary insufficiency and in suspected late-onset adrenogenital syndrome.

Dexamethasone is a glucocorticoid that can suppress the body's own cortisol production. This mechanism is disrupted in patients with an overproduction of cortisol (e.g. Cushing's syndrome). The dexamethasone short test consists of taking dexamethasone at midnight and taking a blood sample in the morning to determine the cortisol level in the blood. If the results are abnormal, further diagnostic measures are required, which your doctor will explain to you.

The GHRH arginine test is used to detect a growth hormone deficiency. The amino acid arginine stimulates growth hormone secretion, as does the growth hormone-releasing hormone GHRH. If the test results are abnormal, an insulin hypoglycaemia test may also need to be carried out.

The insulin hypoglycaemia test is considered the gold standard for testing the corticotropic axis (CRH-ACTH-cortisol release) and the somatotropic axis (growth hormone release). It is used to assess pituitary function, for example in the case of pituitary tumours or after pituitary surgery or radiation. By administering insulin, the blood sugar is lowered to such an extent that hypoglycaemia is produced. This deliberately induced stress event leads to an increased release of cortisol and growth hormone in healthy people. The hypoglycaemia produced can lead to associated symptoms such as restlessness, sweating and malaise.

If diabetes mellitus is suspected, the OGTT is carried out to assess the body's own insulin secretion/effect. After ingesting a sugar-containing solution (75g glucose), the glucose levels as well as insulin and C-peptide in the blood are measured. We also use this test to diagnose insulin resistance or impending diabetes mellitus, e.g. in the context of PCO syndrome. In addition, growth hormone drops in healthy people after the glucose solution is ingested. This does not occur in the case of growth hormone overproduction. The OGTT is therefore also used as a growth hormone suppression test if acromegaly is suspected or to monitor the progress of acromegaly (STH suppression test).

This test is carried out if medullary thyroid carcinoma (MTC) is suspected. A strong increase in calcitonin after stimulation with calcium provides an important indication of the presence of the disease.

This test is performed in cases of suspected hypogonadism with a possible hypothalamic or pituitary cause and to check the functional reserve of gonadotropin secretion. A further indication would be the clarification of pubertas tarda or pubertas praecox.

Indications for carrying out a TRH test would be the suspicion of thyroid hormone resistance or latent hypothyroidism, particularly in the context of fertility diagnostics. The TRH test can also be used to diagnose unclear cases of thyroid dysfunction. Contraindications for this test are known hypersensitivity reactions to TRH, acute myocardial infarction, unstable angina pectoris, epilepsy/increased susceptibility to seizures and severe obstructive bronchial diseases.

This test measures the increase in ACTH and cortisol after application of corticotropin-releasing hormone (CRH). CRH is synthesised in the hypothalamus and selectively stimulates the ACTH-producing cells in the anterior pituitary gland. The test is relevant for the differential diagnosis of Cushing's syndrome and is used in cases of suspected anterior pituitary insufficiency of unknown aetiology and after neurosurgical operations. In addition, the test can be used to check the pituitary-adrenal system after long-term, high-dose glucocorticoid therapy. The test can also be used as part of a combined releasing hormone test (simultaneous administration of CRH, GRH, GnRH, TRH) (see pituitary stimulation test with releasing hormones).

An HKT can be used to check the integrity of the corticotropic, gonadotropic and thyrotropic axes.

CGM stands for "Continuous Glucose Monitoring"

- i.e. "continuous glucose monitoring"

CGM systems are devices that measure the glucose content in the tissue fluid of the subcutaneous fatty tissue every five minutes around the clock. They offer diabetes patients the advantage of not only being able to check their metabolic status at certain points, but also to obtain a 24-hour overview of their daily blood glucose levels. With continuous glucose monitoring, the doctor and patient can also recognise the blood glucose progression at night, assess trends at an early stage and better avoid hypoglycaemia and hyperglycaemia.

How does a CGM work?

The trained user sticks a small glucose sensor through the skin of the upper arm or abdomen using a placement aid, which can remain there for up to seven days. In addition, there is a small electronic unit ("transmitter"), which is fixed to the skin, and a separate display and storage device ("receiver"). Data is transmitted from the measuring system to the display device, which is the size of a mobile phone, by radio. If the CGM system is combined directly with an insulin pump, the display of the insulin pump also serves as a display for the glucose measurement data. These CGM glucose values do not always correspond exactly to the blood glucose values.

Who should consider continuous glucose monitoring?

Before a CGM system can be considered, all other diabetological therapy options must have been exhausted. This includes intensified conventional insulin therapy with multiple injection regimes (ICT) and insulin pump therapy (CSII).

According to the recommendations of the Diabetological Technology Working Group (AGDT) of the German Diabetes Association (DDG), there is an additional benefit in the case of

 hypoglycaemia, i.e. frequent severe hypoglycaemia (with the need for outside help), severe nocturnal hypoglycaemia, proven hypoglycaemia perception disorders

 Unsatisfactory metabolic control if the target HbA1c value is not achieved despite the use of all available treatment options (including CSII), good compliance and exclusion of severe psychological/psychiatric disorders

Source: German Diabetes Aid