An isotope dilution method, using 32P-labeled pyrophosphate, has been developed for the measurement of inorganic pyrophosphate (PP1) in human plasma. The specificity of the method was better than 90% as assessed by elution patterns during ion-exchange chromatography, by paper chromatography, and by incubation with inorganic pyrophosphatase. The 99% confidence limits for a single estimation of plasma PP1 was ±13%. There were no differences in plasma PP1 between men and women, but the values in young people (0-15 yr) were slightly higher than in older people. The mean concentration (±SE) of PP1 in the plasma of 73 men and women was 3.50 ±0.11 μmoles/liter (0.217 ±0.007 μg P/ml) and the normal range (99% limits) was 1.19-5.65 μmoles/liter (0.074-0.350 μg P/ml).
R. G. G. Russell, S. Bisaz, A. Donath, D. B. Morgan, H. Fleisch