The Lack of Relationship between the Calcium, Protein, and Inorganic Phosphorus of the Serum of Non-nephritic Children

It has been shown repeatedly (14) that in cardiac and renal disease, both in adults and children, there is a direct relationship between the levels of serum protein and serum calcium, and also, within limits, an inverse relationship between the serum inorganic phosphorus and the serum calcium (l-5). Peters and Eiserson (4) attempted a mathematical evaluation of the relative effects of protein and phosphorus on serum calcium, intended to permit the prediction of the calcium concentration of the serum in so far as affected by the levels of serum protein and phosphorus. It was assumed that close correspondence between observed and calculated values indicated the absence of direct disturbance of calcium metabolism. More recently, Peters and Van Slyke (6) point out that “the equation (4) must be considered as only a rough first approximation of the effects of phosphate and protein on serum calcium.” The absence of direct relationship between serum protein and serum calcium has, however, been used as a criterion for distinguishing primary disturbances of calcium metabolism (7). It is obvious that the interrelationships of protein, calcium, and inorganic phosphorus in the sera of infants and children cannot be identical with those of adults, for in children, the inorganic phosphorus of the serum is higher, and the protein lower, than in the serum of adults; both of these changes, according to theory, tend to decrease the level of the serum calcium, whereas the serum calcium of the children is usually higher than that of adults. It may be argued that growth itself constitutes a primary alteration in the calcium metabolism, and therefore changes in serum calcium