Pilot quality assurance programme for plasma metanephrines.
BACKGROUND
Up to 2007 there was no formal external quality assurance programme for plasma free metanephrines. A pilot programme was conceived by the AACB (Australian Association of Clinical Biochemists) Working Party on biogenic amines. With support from the AACB and Royal College of Pathologists of Australasia Quality Assurance programmes, a pilot study was developed. Data from this study are presented for the first time.


METHODS
Twelve lyophilized plasma samples were distributed to 15 centres. Samples were spiked with metanephrine (metadrenaline), normetanephrine (normetadrenaline) and 3-methoxytyramine, all derived from human urine. Concentrations were arranged in a linear relationship. The analytes were present at six levels and samples were duplicated.


RESULTS
High-pressure liquid chromatography and tandem mass spectrometry methods showed acceptable precision but in general enzyme immunoassay displayed a higher degree of imprecision as well as a negative bias.


CONCLUSIONS
Differences in calibration and matrix effects are likely to have been responsible for the discrepancy between chromatographic and immunoassay methods. These differences need to be further examined although efforts at standardization between different methods have been hampered by the lack of a universal calibrator for plasma metanephrines. Meanwhile, a laboratory's performance characteristics can be monitored and enhanced by participation in suitable external quality assurance programmes.
Department of Clinical Chemistry, SEALS, The Prince of Wales Hospital, Randwick, Australia. dpillai@nsccahs.health.nsw.gov.au
Dilo
D
Pillai
Shaw
S
Callen
D001679:Biogenic Amines / Q000652:urine; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004298:Dopamine / Q000031:analogs & derivatives / Q000652:urine; D005240:Feasibility Studies; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods; D008676:Metanephrine / Q000097:blood* / Q000652:urine; D009647:Normetanephrine / Q000097:blood* / Q000652:urine; D010865:Pilot Projects; D011786:Quality Control; D012015:Reference Standards; D053719:Tandem Mass Spectrometry / Q000379:methods*
D001679:Biogenic Amines; D009647:Normetanephrine; D008676:Metanephrine; C001746:3-methoxytyramine; D004298:Dopamine