title: Elevated platelet norepinephrine concentration in patients with pheochromocytomas.
abstract: With a radioenzymatic method of analysis we determined the concentration of plasma and platelet norepinephrine in simultaneously drawn blood samples from six patients with pheochromocytomas. All six subjects had elevated platelet norepinephrine concentrations in the preoperative or intraoperative period. Three of the six patients had a normal plasma norepinephrine concentration in their sample. After resection of benign pheochromocytomas the platelet and plasma norepinephrine of five patients returned to normal. The platelet and plasma norepinephrine concentration of a patient with a malignant, non-resectable pheochromocytoma remained elevated. Eight of 30 patients (27%) with hypertension, not thought to be due to pheochromocytoma, had elevated platelet norepinephrine concentrations, All 8 of these patients had diastolic blood pressures of 120 mm Hg or greater at the time the blood samples were drawn. In contrast, the six patients with pheochromocytomas had elevated platelet norepinephrine concentrations while normotensive. Only five of 60 "sick" patients (8%) without a history of hypertension had elevated platelet norepinephrine concentration. Platelet norepinephrine concentration is an excellent test to screen patients, with a history of spells of hypertension but presently normotensive, for pheochromocytomas. An elevated value should be followed up with measurement of vanillylmandelic acid (VMA) and/or catecholamines in a 24-h urine collection.
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000097:blood* / Q000652:urine; D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000032:analysis*; D004837:Epinephrine / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood* / Q000652:urine; D010673:Pheochromocytoma / Q000097:blood* / Q000652:urine; D012016:Reference Values; D014642:Vanilmandelic Acid / Q000652:urine
chemical_list: D014642:Vanilmandelic Acid; D009638:Norepinephrine; D004837:Epinephrine