Clonidine inhibition test

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The clonidine inhibition test , also known as the clonidine suppression test , is a diagnostic test to determine autonomous catecholamine production , as occurs, for example, in pheochromocytoma .

indication

An excess of catecholamines ( adrenaline and noradrenaline ) is often responsible for high blood pressure . Determining the cause of the high concentration is a prerequisite for successful high blood pressure therapy.

principle

Clonidine stimulates α2 receptors in the CNS. This reduces the release of catecholamines in the body. Since the production of catecholamines in a pheochromocytoma is not controlled by the central nervous system, the plasma level of adrenaline and noradrenaline does not decrease when clonidine is administered .

execution

After stopping all antihypertensive drugs ( e.g. beta-blockers ), a blood sample is used to determine the basal level of catecholamines.

Reference values: adrenaline in plasma: up to 50 pg / ml, noradrenaline in plasma: up to 400 pg / ml.

Then 300 µg clonidine is administered in tablet form. Then further blood samples after 60, 120 and 180 minutes. A reduction in catecholemia to below 50% of the basal value is to be expected. If the level does not or hardly drops, this can speak for a pheochromocytoma.

literature

• Diehl, Classen, Kochsiek: Internal medicine . Urban & Fischer in Elsevier, Munich 2006, ISBN 978-3-437-44405-0

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