Use of values of phosphatase activity in the serum as an index of hepatic function was first studied by Roberts,1 in 1933. who found that there was a marked increase of alkaline phosphatase activity with obstructive jaundice, a slight increase with catarrhal jaundice and no increase with hemolytic jaundice. He stated the belief at this time that, in addition to indicating an increased osteoplastic activity, an increased alkaline serum phosphatase activity might also act as a differential diagnostic measure in some types of hepatic disease.
In 1934 Davies,2 Bamann and Riedel3 found that the spleen, kidneys and liver of swine and cattle contained phosphatases which had optimum activities at two ranges of ph. One of these was at approximately ph 4.8 and the other at ph 9 to 9.5.
After the original demonstrations of phosphatases with optimum activities at two ranges of ph