Automated quantification of bone and liver alkaline phosphatase isoenzymes of human serum

Coupling two Technicon AAII samplers synchronised at 50 per hour with a 2 : 1 sample to wash ratio, sera are denatured and collected automatically. The incubation is done in continuous flow by passage through a U device made of large metallic needles soaked in a water bath at 60 +/- 0.1 degree C. This allows a very quick temperature equilibration and a very reproducible incubation time of 35 sec. Initial and residual activities of alkaline phosphatase (ALP: EC 3.1.3.1) are measured on a Rotochem II (Aminco) with the procedure recommended by the Société Française de Biologie Clinique (SFBC). For a mixture of bone and liver ALP, the initial rate constant of heat denaturation Kapp = (A X Kb) + (B X Kl), where A and B are the fractions of each isoenzyme in the mixture, and Kb and Kl the rate constants for bone (b) and liver (l) experimentally determined as 1.8 min-1 and 0.45 min-1 respectively. An equation was derived which converts the percent residual activity to a percentage of bone and liver isoenzyme: % bone ALP = 183--2.38 X % residual activity. This automated method was applied to 2700 people of both sexes from 4 to 100 years old.