Heat inactivable fraction of alkaline phosphatase in marrow and peripheral blood.

We measured the total alkaline phosphatase activity and their heat-inactivable and heat-stable fractions both in marrow and in peripheral blood, collected from 16 patients undergoing bone marrow aspiration for diagnostic purposes. Total enzymatic activity and the heat-inactivable fraction, of bone source, were significantly higher in serum from medullary blood (p < 0.001). Although the heat-stable fraction, of non-bone source, was higher in serum from peripheral blood (p < 0.05), the inactivable fraction showed there the greater component (51.56 +/- 11.91%). Results seem to indicate that the quantification of the enzymatic fractions and of the ratios between them in comparison with marrow and peripheral blood may be useful in cases that pose diagnostic difficulties.