Rapid semiautomated method for the differential determination of urinary catecholamines.

A semiautomated method is presented for the determination of adrenaline and noradrenaline by a combination of the trihydroxyindole procedure for total catecholamines and a new procedure for the specific direct determination of adrenaline without interference from noradrenaline at physiological levels. This new procedure involves the reaction of adrenaline with alkaline thiosemicarbazide to produce a fluorophor of acceptable stability for use in automated procedures. Its structure is as yet unknown. The within-batch standard deviation for the trihydroxyindole and alkaline thiosemicarbazide procedures respectively were 0.005 mumol/24h at a concentration of 0.368 mumol/24h and 0.012 mumol/24h at a concentration of 0.133 mumol/24h. The between-batch standard deviations of the two procedures were respectively 0.018 mumol/24h at a concentration of 0.388 mumol/24h and 0.015 mumol/24h at a concentration of 0.111 mumol/24h. Normal ranges for urine are presented for 24 healthy ambulant laboratory staff. The total catecholamine concentration (calculated as adrenaline) was 0.452 +/- 0.069 mumol/24/ (SD), range 0.349-0.616 mumol/24h. Using the alkaline thiosemicarbazide procedure, the normal range which was determined for adrenaline was 0.100 +/- 0.054 mumol/24h, range 0.022-0.207 mumol/24h. Noradrenaline calculated by difference was 0.355 +/- 0.081 mumol/24h, range 0.195-0.497 mumol/24h.