Function tests

• Suspicion of partial or complete insufficiency of the anterior lobe of the pituitary gland
• Clarification of the functioning of the anterior lobe of pituitary gland after neuro-surgical removal of a pituitary adenoma.

Please note:

• On suspicion of overactivity of partial functions of the pituitary gland, the combined stimulation test should not be used. Instead, individual function-tests should be carried out.
• Usually the order of malfunction of hypophyseal hormone secretion is as follows: STH, LH/FSH, TSH, ACTH
• A regular ovulatory cycle in women usually rules out insufficiencies of the anterior lobe of the pituitary gland
• Most common are partial insufficiencies, especially in hypothalamus-hypophyseal tumors. Clinically these are often less apparent.
• Indication for insufficiencies of the anterior lobe of the pituitary gland: moderate normochromic anemia, low glucose levels, tendency of hyponatremia and hyperkalemia, elevated cholesterol-levels.

TRH-test:

Instable angina pectoris, fresh myocardial infarction, epilepsy, severe obstructive diseases of airways, allergy to TRH (rare).

Gn-RH-test:

Hypersensitivity to GnRH (rare)

Releasing-hormones CRH, TRH, Gn-RH and GH-RH are produced in the pituitary gland and stimulate release of hypophyseal hormones LH, FSH, ACTH, TSH, prolactin and growth hormone STH

LH, FSH, ACTH, cortisol, TSH, prolactin, growth hormone

All hormones are tested with 5ml serum with the exception of ACTH. For the specification of this sending of 2 ml frozen EDTA-plasma is required.

Sexual hormone supplements should be discontinued at least 3 weeks prior to the Gn-RH test.

Taking of bloods in the morning in fasting patient or after a light breakfast.

Insert indwelling venous catheter.

1. First blood extraction after a 30 min break.
2. Then consecutive i.v. injections of: 100 µg pure CRH (Corticorelin, CRH-Ferring®). 200 µg TRH (Protirelin, i.e. Antepan®, Thyroliberin TRH-Merck®, TRH Berlin Chemie®, TRH Ferring®). 100 µg (men) und 25 µg (women) GnRH 1-44 (Gonadorelin, (LHRH-Ferring®, Relefact-LH-RH®). 50 µg GHRH (Somatorelin, GHRH-Ferring®) in short order.
3. For the timings of blood extractions and hormone evaluation please see table below.

Side effects:

GH-RH:

Approximately one quarter of patients experience facial flushing or a metallic taste on the tongue.

Gn-RH:

Hypersensitivity (rare)

CRH:

Following CRH-administration patients might experience facial- and upper body heat sensation as well as an increase of respiratory frequency.

Rarely allergic reactions.

On suspicion of adrenal insufficiency, 30 mg hydrocortisone should be administered after the end of test.

Normal GH-RH test:

Increase of the growth hormone levels to > 10 µg/l (20 mIE/ml).

Normal Gn-RH test:

Women:

(During proliferative stage): increase of the LH-levels to triple the amount, and of the FSH-levels to double the amount of the basal value.

Men:

Increase of the LH-levels to double- up to four times the amount, and of the FSH-levels to double the amount of the basal value.

Normal CRH-test:

A marked increase of cortisol and ACTH indicates normal functioning of the corticotropic cells in the anterior lobe of the pituitary gland (ACTH-increase shows significant individual, partially genetics-related differences).

Insufficiency of:

Please refer to the individual stimulation-tests CRH, GH-RH, Gn-RH and TRH-test.

Frequent problems on the diagnosis of insufficiency anterior lobe of the pituitary gland:

Initially there may only be partial insufficiency. However, additional dysfunctions may develop in the course of further progress. This applies to patients with hypophyseal tumors as well as idiopathic STH-deficiency.

Index:                         

Time of blood extraction and hormone evaluation: