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.
Cattozzo
Giampaolo
G
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
Albeni
Chiara
C
Franzini
Carlo
C
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