CATECHOLAMINES - plasma

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Specimen: The patient should rest for 30 minutes after insertion of an indwelling cannula, to allow return to a basal state. 10 mL blood in an EDTA tube. Some laboratories require a special EDTA/metabisulphite tube. Specimen must be transported rapidly to the laboratory on melting ice, centrifuged without delay, and the plasma stored frozen.

Method: HPLC, radiometric assay.

Reference Interval: Varies with laboratory, typically:

Adrenaline:	<0.3 nmol/L
Noradrenaline:	<2.5 nmol/L
Dopamine:	<0.5 nmol/L

Application: Used as an alternative to urine catecholamine studies in the diagnosis of phaeochromocytoma (adrenaline, noradrenaline) or neuroblastoma (dopamine).

Interpretation: Elevated levels suggest the presence of tumour. If clinical uncertainty exists and the tumour cannot be located by diagnostic imaging, a clonidine suppression test may be indicated. See CLONIDINE SUPPRESSION TEST .

Reference: Sjoberg RJ et al. Arch Int Med 1992; 152: 1193-1197.

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