Endocrine Abstracts

Introduction and aim: Osteopetrosis is a rare genetic disorder of reduced osteoclastic bone resorption. Defective bone remodelling induces skeletal sclerosis and abnormally dense but brittle bones. We present here a case of autosomal dominant osteopetrosis type II as a cause of high bone mineral density (BMD).

Case report: A 52-years-old woman with a complaint of bone pain and headache referred to our clinic for evaluation of high BMD. Her medical history and physical examination were unremarkable. Increased BMD in DXA scanning affecting both spine and hip was classified as generalised and acquired causes were evaluated initially. Serum fluoride concentration, renal and liver function tests, IGF-1 level, hepatitis C serology were all normal excluding fluorosis, renal osteodystrophy, acromegaly, hepatitis C associated osteosclerosis. There was no splenomegaly or hematologic abnormality for miyelofibrosis. Serum tryptase level was normal excluding mastocytosis. She denied any usage of oestrogen implants. Excluding the acquired causes, the specific features suggesting monogenic disorders such as osteopetrosis or sclerosing bone dysplasias were investigated. Rugger-jersey spine due to vertebral end plate thickening, bone within bone in pelvis and transverse sclerotic bands within distal femur, the classic signs of osteopetrosis, were recognized at plain radiographs. She denied any history of fracture and also, whole body radiographic survey showed no pathological fractures. Her serum acid phophatase was high. She was diagnosed as adult type osteopetrosis type II. Complication screening revealed only mild decrease in high-pitched voice in audiology.

Conclusion: Autosomal dominant osteopetrosis exhibits a heterogeneous trait with milder symptoms, often diagnosed at later adolescence or adulthood. Two distinct types (type I and II) have been described on the basis of radiographic, biochemical and clinical features. Type II disease appears to increase the risk of fracture. The disease requires no treatment although the complications may require intervention.