Every 6 months during the 2-year intervention trial, we will perform interval history, general and joint physical exam, anthropometric measurements (height, weight, BMI), pill counts, MMEM monitor check, DXA scan of total body and lumbar spine for bone mineral density, and dispensing of study drugs. At yearly intervals during the intervention trial, we will do the Youth/Adolescent Questionnaire (YAQ) on diet (which is validated for 1-year recall), 3-day diet diary for current intake, blood tests for mineral and calcitropic hormone concentrations, 24-hour urine for measurements of bone turnover markers and mineral excretion, physical function assessment (JAFAR), and physical activity questionnaire. We will obtain blood for determining vitamin D receptor (VDR) genotype at baseline only. We will perform fasting random urine tests to determine Ca/creatinine ratio to assess for treatment-induced hypercalciuria at months 0, 3, 6, 12, 18, and 24.