Electrophoretic method for assessing the normal and pathological distribution of alkaline phosphatase isoenzymes in serum.

We describe a simple, reproducible, discontinuous system for polyacrylamide disc gel-electrophoresis, with which the alkaline phosphatase isoenzymes in human serum can be fractionated. No sample preparation is needed. The isoenzymes are classified according to their electrophoretic mobilities (R-F values) and quantitated by peak area measurements from spectrophotometric scans. The four alkaline phosphatase isoenzymes usually present in normal sera, in order of descending mobilities (and designated according to principal tissue of origin) are: "fast" liver, "slow" liver, bone, and intestine. Sera of diseased patients show a greater variety of isoenzyme distribution patterns, but the most frequently observed patterns are the same as normal patterns. We conclude that the finding of "fast" liver only is not pathognomonic, as previously reported by others, and that information on relative distributions per se is not diagnostically useful, although information on specific increases in activity is useful. With this system, hepatobiliary disorders can be differentiated from other forms of liver and bone diseases.