Cclxii. the Significance of Phosphatase Estimations in the Adult Fowl. by Douglas William Auchinachie and Arthur Raymond Gordon Emslie

KAY [1930] showed that in certain bone diseases in man the plasma-phosphatase activity is considerably higher than normal. This served as an impetus for investigation into the activity of the enzyme in plasma and tissues under different conditions in man and experimental animals. The literature has been reviewed by Kay [1932] and by Robison [1932], and it is unnecessary to go into it in great detail here. Briefly, it may be said that in healthy young animals the activity of the plasma-phosphatase is higher than it is in the adult, but with the completion of rapid bone formation the value drops to the adult level. This is well illustrated bythe observations of StearnsandWarweg [1933] with children. During the healing of rickets or other bone diseases the initially high plasma-enzyme activity tends to return to the normal for animals of that age and class. Abnormally high values may be observed in jaundice [Roberts, 1933] and possibly also after the ingestion of a high carbohydrate meal [Bodansky, 1934]. When proper precautions are taken it would seem that estimation of the plasmaphosphatase activity may serve in many mammals as a somewhat earlier indication of faulty Ca and P metabolism than do serum-Ca or inorganic P determinations, although high phosphatase values cannot be considered specific for any one disease. Clinically, estimations of tissue-phosphatase activity have a more limited value. Bone-phosphatase activity is high in rickets: it is diminished under prophylactic, and still more under excessive, treatment with vitamin D. Hypervitaminosis D also results in a decrease in the activity of the kidney-phosphatase. It has been shown that the tissue-phosphatase of fowls reacts in a manner similar to that of mammals [Hall and King, 1930-31; King and Hall, 1931]. Within the species, the individual variation of the plasma-phosphatase activity of normal adult mammals is not great [Kay, 1930; Auchinachie and Emslie, 1933]. From the values reported by Common [1934] it would appear that the normal range is wide in adult fowls. From the three values he gives for cockerels one might consider the range in these birds to be narrow, but the laying pullets vary from 6*9 to 27-7 Bodansky [1933] units, or approximately 0'23-0*92 Kay [1930] units'. These birds were considered to be strictly normal White Wyandotte pullets (personal communication) and the question naturally arises as to whether estimations of the plasma(or serum-) phosphatase activity wiRl give any indication of faulty Ca and P metabolism in fowls, or whether there is normally such variation that phosphatase estimations have only a limited significance at the present time.