Non-azotemic refractory rickets in Indian children

In order to examine the etiology of refractory rickets, we evaluated the case records of patients presenting between 1990 and 2002. Subjects with impaired renal functions were excluded. Of 131 patients, 25.9 % each had hypophosphatemic rickets and distal renal tubular acidosis (RTA), 19.6 %vitamin D dependent rickets (VDDR), 11.3 % proximal RTA, 9.1 % liver disease and 6.1 % malabsorption. A significant proportion of patients with VDDR and proximal RTA showed deformities in the first year of life, whereas those with distal RTA and hypophosphatemic rickets presented later. Patients with hypophosphatemic rickets had predominant involvement of lower limbs; hypercalciuria was found in 4. Distal RTA was associated with marked rickets and normal levels of alkaline phosphatase. Hypophosphatemia and low tubular reabsorption of phosphate, though characteristic of hypophosphatemic rickets, was also seen in patients with VDDR (19.2%) and distal RTA (17.6 %). Our findings suggest that application and interpretation of appropriate investigations are useful in determining the cause of non-azotemic refractory rickets allowing initiation of specific therapy.