Evaluation of an immunoradiometric assay for bone alkaline phosphatase mass concentration in human sera.

The performance characteristics of an immunoradiometric assay for bone alkaline phosphatase mass concentration in human sera are reported. Within-run imprecision (n = 20) was 12.1% (mean = 7.8 micrograms/l) and 3.6% (mean = 22.8 micrograms/l), between-day imprecision (n = 8) was 10.1% (mean = 20.3 micrograms/l) and 2.8% (mean = 84.3 micrograms/l). There was a linear relationship between the concentrations of the standards employed and the counts per minute up to 120 micrograms/l. The detection limit was 0.3 micrograms/l. In 102 apparently healthy persons (51 males and 51 females; range of age: 18-56 years) the following reference intervals were established: 3.8-21.3 micrograms/l (males) and 3.4-15.0 micrograms/l (females). We compared the values obtained using the immunoassay with those obtained by precipitating of bone alkaline phosphatase with wheat-germ lectin (alkaline phosphatase activity concentration was determined at + 25 degrees C by the optimized standard method according to the Recommendations of the German Society for Clinical Chemistry). For the reference individuals the relationship between the results of the two methods is given by the following regression equation: Bone alkaline phosphatase activity concentration [U/l] = 14.81 + 3.28 x bone alkaline phosphatase mass concentration [micrograms/l] (r = + 0.783). In 89 sera from 32 patients before and after renal transplantation (range of bone alkaline phosphatase mass concentration: 2-39 micrograms/l) comparison between the two methods yielded a linear correlation coefficient of r = + 0.886.(ABSTRACT TRUNCATED AT 250 WORDS)