Distribution of the Phosphorus Compounds and Calcium in the Blood of Children.

During the past 15 or 20 years our knowledge of the phosphorus content of the human blood has been considerably advanced by the work of several investigators. The inorganic phosphorus fraction, which is only about onetenith of the total phosphorus content of the whole blood, appears to have claimed the attention of most of the previous workers, and, therefore, abundant data are available from the literature both for health and disease. Because of this, the inorganic phosphorus of the blood has already acquired some definite practical clinical value. The other compounds of phosphorus in the blood have attracted, however, the attention of fewer workers. The results of the present investigations are published in the hope of throwing further light on the distribution of phosphorus in the blood of the child, and especially on the quantitative changes resulting from disease. Methods-1. The method used for all the estimatioins of phosphorus compounds was, with one or two slight modifications, that adopted by Kay and 13vrom1. 2. Determinations of the calcium content of the blood serum w-cre made accordilng to the method described by Kramer and Tisdall2. While in studies of this nature it is probably desirable to obtain all the samples of blood in the morning after a whole night's fasting, it proved impracticable in every case to adhere to such a rule. At least 4 hours were allow-ed to elapse after a meal before the sample of blood was taken for analysis. This interval is probably long enough to exclude any direct influence of the meal on the partition of blood phosphorus. \enous blood 1 was used with a minute quantity of potassium oxalate as anti-coagulaiit. As very little is known at present regarding the equilibrium existing between the various forms of the phosphorus in the plasma anid in the red bloodl corpuscles, or the ease Nvith -which an exchange may take place between the corpuscles and the plasma, the analytical procedures were commenced immediately the samples of blood were obtainiedl. Kay and Byrom' used the substance ' Heparin' as the anti-coaguilanlt in the samples of blood for the haematocrit values, and potassium oxalate in that for the estimations of phosphorus compounds. In this study potassium oxalate was invariably use(l. It is true that the osmotic pressure of potassium oxalate is relatively high, and, as Rossdale3 pcinted out, the addition of oxalate reduces the corpuscular volume per 100 c.cm. of blood. But, as oxalate is also used in the separation of plasma from the cells for the estimation of the phosphorus compounds, there is