Bone densitometry of a patient with osteosclerosis

A 30-yr-old Caucasian man with a history of dorsal and lumbar back pain, which responded partially to antiinflammatory agents, was seen at our Unit. The biochemical bone markers showed an increment in bone alkaline phosphatase and urinary CTX. Serum phosphate tended to be low. Radiographic abnormalities were marked osteosclerosis in the pelvis and vertebral bodies without changes in size. Bone scintigraphy results were normal. The increase in bone mineral density (BMD) was greater in L2-L4 (+ 3.9 SDs) than in total skeleton (+ 1.4 SDs). Analysis of skeletal subareas showed a marked increase in axial skeleton BMD: trunk, +4.0 SDs; spine, +2.5 SDs and pelvis, +4.5 SDs. BMD of the remaining subareas was found to be normal: skull, +0.04 SDs; arms, -0.3 SDs and legs, -0.05 SDs. The patient refused to have a bone biopsy. The radiologic, densitometric, and biochemical findings in the patient presented herein are compatible with axial osteomalacia. Evaluation of total skeleton BMD, and especially skeletal subareas, clearly indicated that the abnormal BMD was restricted to the spine and pelvis whereas the rest of the skeleton was not affected.