Correspondence Phosphate deficiency and rickets Sir,

deficiency might be an aetiological factor in neonatal rickets. We agree, and we think also that in some cases of vitamin D deficiency rickets the leaking of phosphate rather than of calcium may be responsible for the bone lesions. Hurwitz et al.2 observed that rats fed a normal calcium diet without vitamin D developed hypocalcaemia and had a slight decrease in bone ash but had no evidence of rickets, whereas when they were given a low phosphate diet with vitamin D, hypophosphataemia and severe bone lesions developed. These findings led us to investigate the severity of the rachitic process (as shown by the level of serum alkaline phosphatase) and the radiological picture of the bones in relation to the serum calcium and phos-phate levels.3 We studied 100 infants who were thought to have vitamin D deficiency and who had been treated wit