A couple unable to conceive after 6 years of marriage and infertility treatment decides to adopt a 2.5 year old orphan girl. The child is brought for a medical examination. Her antenatal and birth history is unknown. She was received by the orphanage as a newborn and had begun walking at 27 months. She also has delayed speech and dentition. On examination, she was found to be severely malnourished and stunted with a waddling gait and pigeon chest. X-rays of her extremities are shown. Investigations reveal normal serum calcium, increased phosphates and alkaline phosphatase levels and elevated parathyroid hormone levels.

Vitamin D levels were not measured. Hemoglobin was 9.8gm/dl and other investigations were normal. What should be the initial treatment? Source: RB. ISLINGER, WG. MACKENZIE, July 15, 1996. Clinical case presentation.