Co-existence of osteogenesis imperfecta and hyperparathyroidism.

Osteogenesis imperfecta (OI) and hyperparathyroidism (HTP) are disorders affecting the skeletal system and calcium metabolism not evidently related to one another. We report a case in which both OI and HPT were present. Our female patient presented with hypercalcaemia (S-Ca2+ 1.59 mmol/l; normal range 1.15-1.30) and 4-gland parathyroid hyperplasia at 30 years of age. Since her first year she had fractures, blue sclera, hypermobile joints, short stature (height 1.51 m, weight 49.5 kg) but normal hearing, and dentiogenesis imperfecta (tooth disease caused by defective formation of dentin) was absent. This patient bears many similarities with the 5 patients reported previously but it is the only patient, to our knowledge, with OI and early onset of HPT (30 year old female). We have found the OI to be type 1. A minor improvement of the rate of bone turnover 10 months after parathyroidectomy indicates the HPT to be primary and suggests the OI type 1 and pHPT to be two different calcium metabolic diseases incidentally occurring in the same patient.