A 10-year-old boy has a fracture of the femur. The biochemical evaluation revealed Hb 11.5 gm/dl and ESR 18 mm 1 hour, serum calcium 12.8 mg/dl, serum phosphorus 2.3 mg/dl, alkaline phosphatase 28 KA units and blood urea 32 mg/dl. Which of the following is the most probable diagnosis in his case?