Hyperparathyroidism and Bone Health.

Bone pain, proximal muscle weakness, skeletal deformities, and pathological fractures are features of osteitis fibrosa cystica which occur in severe primary hyperparathyroidism (PHPT). In this condition, bone mineral density is usually extremely low, but may be reversible after parathyroidectomy. On X-ray, bone abnormalities are described as having a salt-and-pepper appearance in the skull, with bone erosions and resorption of the phalanges, brown tumors and cysts, as well as diffuse demineralization, along with pathological fractures, particularly in the long bones of the extremities. A marked elevation of the serum calcium and PTH concentrations is seen, and renal involvement is manifested by nephrolithiasis and nephrocalcinosis. In asymptomatic PHPT, the absence of clinically significant bone involvement has led to much more data on bone mineral density becoming available by dual X-ray absorptiometry (DXA) and also on new technologies such as trabecular bone score (TBS), which is a gray-level textural analysis of DXA images that provides an indirect index of trabecular microarchitecture. In addition, high-resolution peripheral computed tomography (HRpQCT), which has a low radiation exposure, provides further understanding of the microstructural skeletal features at both trabecular and cortical sites.