A tale of three diseases of the bone.

Paget's disease is a relatively rare disorder of the bone with only a few reports and case series observations from India. Hypocalcaemia is rare in Paget's disease, usually occurring as a consequence of therapy with bisphosphonates. We report a 65-year-old woman with Paget's disease who had hypocalcaemia secondary to vitamin D deficiency. On further evaluation, she also had severe osteoporosis. How vitamin D deficiency affects the diagnosis and monitoring of Paget's disease and the relationship between the three diseases are discussed. This case illustrates an interesting situation with abnormal bone turnover, remodelling and mineralisation in the form of Paget's disease with osteomalacia and osteoporosis.