Catecholamines

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:

Have been used as an alternative to urine catecholamine studies in the diagnosis of Phaeochromocytoma (adrenaline, noradrenaline) or Neuroblastoma (dopamine). However, urine catecholamines or metanephrines are used more often. See Catecholamines urine and Metanephrines urine.

Plasma metanephrine assays are the preferred first line tests for Pheochromocytoma.

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:

Lenders JW et al. Ann N Y Acad Sci 2002; 970: 29-40.