A 10-year-old boy has a fracture of the femur. the biochemical evaluation revealed Hb 11.5 gm/dL, and ESR 18 Mini Ist hour. Serum calcium 12.8mg/dL, serum phosphorus 2.3 ing/dL, alkaline phosphatase 28 KA units and blood urea 32 mg/dL. Which of the following is the most probable diagnosis in his case-