The Effect of a Continuous Intravenous Infusion of Inorganic Phosphate on the Rachitic Lesions in Cystinosis.

Fraser, Jaco, Yendt, Munn and Liu (1957) and Fraser, Geiger, Munn, Slater, Jahn and Liu (1958) reported healing of rachitic lesions in vitamin Ddeficient and in hypophosphataemic refractory rickets by intravenous administration of phosphate. The concentration of serum inorganic phosphorus, which initially had been very low, was kept at normal levels for a period of five to seven days. The authors concluded that vitamin D was not obligatory for healing in these types of rickets. The metabolic defect in cystinosis leading to severe amino-aciduria, glycosuria, metabolic acidosis and deposition of cystine crystals in various organs, in addition to hypophosphataemia and rickets, is undoubtedly more severe than in infantile and primary refractory rickets. But there is no valid reason to suppose that the pathogenesis of rachitic lesions is different from that in other types of rickets, in which an insufficiency of calcium and a low concentration of serum inorganic phosphorus inhibit proper calcification of the bone matrix. However, this has never been proved. It was therefore decided to find out whether improved calcification could be obtained by inducing a lasting rise in the concentration of serum phosphorus in the absence of vitamin D and alkalizing agents. Simultaneously, the effect of the induced rise in the concentration of serum phosphorus on the concentration of serum calcium and on the product of these concentrations was studied.