STH suppression test

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The STH suppression test is used to detect impaired somatotropin regulation in the diagnosis or monitoring of the progression of acromegaly .

Test principle

The added glucose increases the blood glucose concentration. Under physiological conditions, this increase leads to a suppression of the hypophyseal STH secretion. The STH level in the blood drops. In patients with acromegaly, this counter-regulation mechanism is suspended. The STH level remains high.


The test is carried out in the morning between 8:00 and 9:00 on an empty patient.

  • Blood sampling for glucose and STH determination (capillary or venous blood)
  • Then oral administration of 100 g glucose, which was dissolved in approx. 400 ml water. The liquid must be drunk within 5 minutes.
  • Blood sampling for glucose and STH determination after 60, 90 and 120 minutes


In healthy people, the STH level drops to below 2 ng / ml after glucose exposure. In acromegaly patients, there is at best a slight decrease that does not fall below a limit value of 5 ng / ml.

Cave : The STH suppression test alone does not reliably detect acromegaly. A lack of STH suppression also occurs with other underlying diseases (e.g. Wilson's disease , renal insufficiency , acute intermittent porphyria ).