Harmonization of values for serum alkaline phosphatase catalytic activity concentration employing commutable calibration materials.
BACKGROUND
Harmonization of results allows a more effective utilization of laboratory tests; we verified the feasibility of harmonizing serum alkaline phosphatase results by two methods.


METHODS
Patient sera (n=106) and candidate calibration materials (n=8) were analyzed by two methods, employing either diethanolamine (DEA) or 2-amino-2-methyl-1-propanol (AMP) as phosphate-accepting buffers. Results for patient sera by the DEA method were recalculated, with either a commutable or a non-commutable calibration material, both with values assigned by the AMP method.


RESULTS
After calibration with the commutable material, the median intermethod difference (DEA-AMP) and ratio (DEA/AMP) dropped from 195 U/l to 0 U/l and from 2.47 to 1.00, respectively. When a non-commutable material was used the former became 124 U/l and the latter 1.94. After recalibration with the commutable material, linear regression and correlation analysis of DEA vs AMP values for the set of 106 patient sera gave: intercept=0.8 U/l; slope=0.997; and nonparametric correlation coefficient r=0.9995.


CONCLUSIONS
Harmonization of alkaline phosphatase results by AMP and DEA methods is feasible when commutable calibration materials are used in the trueness transfer process.
Laboratorio di Analisi Ospedale Filippo Del Ponte, Azienda Ospedaliera Ospedale di Circolo e Fondazione Macchi, Via Filippo Del Ponte 19, 21100 Varese, Italy. giampaolo.cattozzo@gmail.com
Giampaolo
G
Cattozzo
Chiara
C
Albeni
Carlo
C
Franzini
D000469:Alkaline Phosphatase / Q000097:blood* / Q000592:standards; D002138:Calibration; D002384:Catalysis; D004789:Enzyme Activation / Q000502:physiology; D004983:Ethanolamines / Q000032:analysis* / Q000592:standards; D006801:Humans; D011412:Propanolamines / Q000032:analysis* / Q000592:standards; D013678:Technology, Pharmaceutical / Q000379:methods / Q000592:standards*
D004983:Ethanolamines; D011412:Propanolamines; C020283:diethanolamine; D000469:Alkaline Phosphatase; C006551:2-amino-2-methyl-1-propanol