Trh test $$$

Test procedure to check the TSH secretion reserve in borderline thyroid dysfunction such as preclinical hypo- or hyperthyroidism. Note: due to the high quality TSH assays this test is usually unnecessary.

Further indications:

Detection of secretion rigidity in TSH-producing tumours.

Detection of thyroid hormone resistance (excessive stimulation)

Contraindication: Known hypersensitivity to TRH; spasms, severe obstructive bronchial diseases, unstable angina pectoris, fresh myocardial infarction

In the TRH test, the basal TSH value in the blood is measured first. Then 200 µg thyrooliberine is slowly injected intravenously. After 30 minutes another blood sample is taken to determine the TSH value again.

Reference values for the laboratory value TRH:

• TSH increase: > 2.5 times the base value
• TSH maximum: < 25 mU/ml

Absence or reduction of increase: hyperthyroidism, autonomy, secondary (pituitary) hypothyroidism, suppression of hypothalamic function by SD thyroid medication

Excessive increase: subclinical hypothyroidism, primary hypothyroidism, SD hormone resistance

Böhm O (2018) Thyroid hormones. In: Neumeister B et al (Eds) Clinical guide to laboratory diagnostics. Elsevier GmbH S. 299-300