The plasma free metadrenalines test measures the amount of metadrenaline and normetadrenaline in the blood. These substances are metabolites of adrenaline (epinephrine) and noradrenaline (norepinephrine). Adrenaline and noradrenaline are catecholamine hormones that help regulate blood pressure.
Catecholamines are produced in the adrenal medulla – the interior portion of the – and secreted into the blood. Once these...
The plasma free metadrenalines test measures the amount of metadrenaline and normetadrenaline in the blood. These substances are metabolites of adrenaline (epinephrine) and noradrenaline (norepinephrine). Adrenaline and noradrenaline are catecholamine hormones that help regulate blood pressure.
Catecholamines are produced in the adrenal medulla – the interior portion of the – and secreted into the blood. Once these hormones have completed their actions, they are metabolised to inactive compounds. Noradrenaline breaks down into normetadrenaline and hydroxymethylmandelic acid (HMMA) (also called vanillylmandelic acid (VMA)), and adrenaline becomes metadrenaline and HMMA. Both of the catecholamines and their metabolites are normally found in small fluctuating quantities in the blood and urine.
A rare tumour called a can produce large amounts of catecholamines, resulting in significantly increased concentrations of metadrenaline and normetadrenaline. About 80-85% of phaeochromocytomas form in the adrenal glands and, while a few are cancerous, most are – they continue to grow but usually do not spread beyond their original location.
The catecholamines produced by phaeochromocytomas can cause persistent hypertension and episodes of severe high blood pressure. This can cause symptoms such as headaches, palpitations, sweating, nausea, anxiety, and tingling in the extremities. Left untreated, the symptoms may worsen as the pheochromocytoma grows. Over time, hypertension caused by the tumour may cause kidney damage, heart disease, and raise the risk of a stroke or heart attack.
Several tests, including plasma free metadrenalines, can detect the presence of phaeochromocytomas. Although they are rare, it is important to diagnose these tumours because they cause a potentially curable form of hypertension. In most cases, the pheochromocytomas can be surgically removed, which eliminates the high blood pressure and its associated symptoms and complications.