[Plasma methoxyamines assay: a practical advance for the diagnosis of pheochromocytoma].
Measurement of plasma methoxyamines is aimed to provide a reliable plasma marker readily available for any patient suspected of having a pheochromocytoma. The present HPLC method is able to detect methoxyamine amounts as low as 0.2 nmoles/l and allows the determination of both free or conjugated methoxyamines (metanephrine MN and normetanephrine NMN) in normal subjects, treated or untreated patients and a fortiori in pheochromocytoma. The analytical specificity is excellent. Among most usual antihypertensive drugs, only conversion enzyme inhibitors and diuretics induce in some patients a moderate increase of NMN with minor consequence in values interpretation. The kidney plays a major role in the blood clearance of methoxyamines and any alteration of renal function is associated to the increase of plasma methoxyamine levels. Plasma methoxyamines have a long half-life and are long-lasting integrated markers of catecholamine secretion; at variance with plasma free catecholamines, they are able to afford the presence of a secreting pheochromocytoma whatever the clinical presentation--asymptomatic or paroxysmal form between the crisis. The diagnostic sensitivity (at least 98%) is equal to that of urinary methoxyamines, far higher than plasma or urine catecholamines or urine VMA (60 to 70%).
Peyrin
L
L
Laboratoire de Physiologie, Faculté de Médecine, Lyon, France.
Cottet-Emard
J M
JM
Pagliari
R
R
Cottet-Emard
R M
RM
Badet
C
C
Mornex
R
R
D000310:Adrenal Gland Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000601:surgery; D000328:Adult; D000368:Aged; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D002851:Chromatography, High Pressure Liquid; D004232:Diuretics / Q000627:therapeutic use; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000188:drug therapy; D008297:Male; D008676:Metanephrine / Q000097:blood*; D008875:Middle Aged; D009647:Normetanephrine / Q000097:blood*; D010673:Pheochromocytoma / Q000097:blood / Q000175:diagnosis* / Q000601:surgery; D012016:Reference Values; D051437:Renal Insufficiency / Q000097:blood
D000806:Angiotensin-Converting Enzyme Inhibitors; D004232:Diuretics; D009647:Normetanephrine; D008676:Metanephrine
Le dosage des méthoxyamines plasmatiques: une avancée pratique dans le diagnostic du phéochromocytome.