Endocrine Abstracts

Introduction: Osteogenesis imperfecta also known as Lobstein’s disease (LD) is a rare disorder of type 1 collagen characterized by an increased susceptibility to bone fractures. Its coexistencewith primary hyperparathyroidism (PHP) was rarely described. Herein we report a new case of a primary hyperparathyroidismin a patient with a history of Lobstein’s disease.

Observation: A 35-year-old woman was referred to our departmentfor hypercalcemia. Her past medical history included osteogenesis imperfecta type I diagnosed at the age of 8 years and recurrent urinary tract infections due to a vesicoureteral reflux. She presented with nausea, vomiting, constipation, bone pain, muscle weakness and depression. On examination, she had a body weight of 70 kg, a short stature, a body mass index of 28.39 kg/m², a blue sclera, a blood pressure of 100/60 mmHg and a regular pulse of 75 beats/min. The laboratory investigations showed a serum calcium level of 114 mg /L(normal range: 85–105), a urinary calcium level of 330 mg/24 h, a phosphate level of 17 mg/l (normal range: 25–45), a creatinine level of 7 mg/l, a magnesium level of 21 mg/l (normal range:16–26 mg/l) , a serum albumin of 34 g/L (normal range: 38–56), a Vitamin D deficiency (25 OH Vitamin D level of 5,5 μg/L, normal range: 30–80 μg/L) and an elevated parathormone level of 626 pg/ml (normal range: 10–65 pg/ml). Radiographs of long bones showed cortical bone thinning and excessive trabecular bone transparency. Bone densitometry revealed osteoporosis. Cervical ultrasound and parathyroid scintigraphy were normal. Cervical computed tomography disclosed a left superior parathyroid adenoma. Parathyroid adenomectomy was performed to the patient. After surgery, serum calcium and PTH level were normal (91 mg/l, 29 pg/ml, respectively).

Conclusion: PHP and LD are two disorders affecting the skeletal system and the calcium metabolism. Their coexistence seems to be a chance occurrence. However, it has been suggested that LD may predispose to PHP. In fact, the lifelong disorder of skeletal homeostasis in LD may lead to a secondary hyperparathyroidism and then to autonomous parathyroid tumor formation.