Seasonal tide of blood phosphate in infants

Abstract

In a previous communication it was shown that in infants the inorganic phosphate of the blood could be raised to the normal level by frequent exposures to the sun's rays. 1 The same result can be brought about by means of the carbon arclamp. The most effective radiation in bringing about this alteration are the ultraviolet rays. As has been shown by Dorno, the rays of the sunduring the summer are incomparably richer in ultraviolet than those during the winter and early spring. It seemed, therefore, of interest to follow, month by month, the content of inorganic phosphate in the blood of a group of infants, where dietetic and hygienic conditions could be controlled. The accompanying tables indicate the result of a systematic study of this kind. Table I shows that in June and July of last year the average inorganic phosphate of the blood of these infants, who varied in age from about 6 to 18 months, was 4.35 mg. per cent. During the summer and fall analyses were not carried out. In December the average percentage had fallen to 3.92 mg., and then decreased steadily during January, February and March. In April, especially during its latter half, and in the first half of May, the inorganic phosphate again began to rise. These averages represent some 270 individual tests. Table II shows that the high percentages in the summer and the fall, and the steady and marked ebb during the winter months, occur quite irrespective of the nature of the diet. This seasonal tide of the blood phosphate is to be attributed mainly to the seasonal variation of sunlight. It would seem that the ultraviolet rays are necessary for the normal metabolism of the growing infant, especially in relation to its exchange of inorganic salts.