How to assess Vit. D therapy in Rickets is

Following adequate Vitamin D therapy,most patients with vitamin D deficiency rickets show radiological evidence of healing within 4 weeks.X-ray wrist is taken for this purpose.Reduction in blood levels of alkaline phosphatase and resolution of clinical signs occur slowly.If radiological healing cannot be demonstrated,despite 1-2 large doses of vitamin D,patients should be evaluated for refractory rickets. Vitamin D- deficiency rickets at presentation (upper) and 3 months after vitamin D and calcium therapy (lower) in a 1-year old black boy. At presentation, radiographs of the wrist (left) and knee (right) showed evidence of splaying, fraying, cupping, and demineralization of the distal radial and ulnar metaphyses, the distal metaphysis of the femur, and proximal metaphyses of the tibia and fibula. There was widening of the physis. After therapy, the child showed evidence of near-complete resolution of metaphyseal fraying with interval development of a dense provisional zone of calcification in the metaphysis consistent with healing rickets. Reference:Essential pediatrics-Ghai,8th edition,page no:114.