Concentration of Calcium and Phosphorus in the Serum of Children

Abstract

Data on calcium and phosphorus 1 of the serums of 250 healthy children from 5 to 16 years of age were analyzed in an investigation of dental caries.2 This gave us an opportunity of studying the physiologic relation of these substances to such factors as age, sex and development and their physiologic variation. METHODSAfter the children had rested for at least fifteen minutes, blood was withdrawn with as little stasis as possible. It was not collected under oil. As soon as the blood clotted, the specimens were centrifugated, and the serum was separated from them. All determinations were made immediately after the collection of the blood. Duplicates for calcium were done, except in a few cases.Calcium.\p=m-\Amodification of the Clark-Collip method,3 involving the adjustment of the ph to about 5, and two washings of the precipitate were used. The average deviation of duplicates was 0.25 mg. per hundred cubic centimeters (about 3.6 per cent).Phosphorus.\p=m-\Inthe great majority of the cases the Tisdall method4 was used. Duplicates with this method showed an average difference of 2.6 per cent. The Fiske-Subbarrow method5 was employed in 8 cases ; the average difference between duplicates was 1.9 per cent. The results obtained with the Tisdall and From the