Function tests

Growth hormone producing tumor (acromegaly)

Pituitary macro adenoma

Administration of TRH (as well as in case of an existing primary hypothyroidism) under physiological conditions leads to a suppression of growth hormones, however in case of an existing STH producing pituitary adenoma, it can lead to a paradox stimulation in 50 % of the cases.

Growth hormone (STH), prolactin

2 ml serum each, before and 30 min after TRH injection for evaluation of growth hormone and prolactin (to document sufficient stimulation).

In the mornings, patient empty-stomached.

1. Blood collection before intravenous TRH injection

2. Intravenous administration of 200 µg TRH (Children 1 µg / kg body weight)

3. Blood collection after 30 min

Paradox increase of STH of at least 50% indicates hypophyseal acromegaly.

The specificity of this test lies at 100%, sensitivity only at 50%. This means, that hypophyseal acromegaly can safely be assumed if there is a positive test result (paradox stimulability), whilst acromegaly is apparent in 50% of cases with a negative test result (missing stimulability), meaning that a negative test result does not allow an unequivocal statement.

A stimulation of prolactin by at least 50% indicates that the test process was valid.