Bone densitometry: patients with asymptomatic primary hyperparathyroidism part I. Technical report

Many studies document bone loss at diagnosis in patients with PHPT (including mild PHPT) that is greater than would be expected in comparable persons without this condition. However, there is no general agreement regarding the severity of bone mass loss in these patients and the rate at which it progresses. A few studies suggest that such accelerated osteoporosis may be self-limited, with patients showing no further decline in BMD after diagnosis. There is insufficient evidence to conclude that PTH-related bone loss is associated with an increased risk of fracture. The few studies that have evaluated the risk of fracture in these patients are conflicting. Some evidence also suggest that, like bone loss in these patients, fracture risk may change during the course of the disease. One study found that patients with PHPT (including those with mild hypercalcemia) were more likely than matched controls to have a history of fractures prior to diagnosis, but that both groups had similar rates of fractures during followup. Moreover, the studies of fractures suffer from several limitations, such as nonrandomization of patients, different definitions of vertebral fractures, small study populations, and short followup times. There is also insufficient evidence to determine the effect of parathyroidectomy on the incidence of fractures in patients with mild PHPT, partly because the natural history of this condition is incompletely understood. Although studies demonstrate that patients with PHPT gain bone mass following parathyroidectomy, the bone reparation is incomplete and bone mass density remains below normal, even though the hyperparathyroidism is cured. Currently, decisions to perform parathyroidectomy are based on signs and symptoms of bone disease, metabolically active renal stones, decreased renal function, fatigue and/or depression, and high levels of serum calcium. Although the use of bone mass measurements has been advocated to aid clinical decisions regarding the risks and benefits of surgery, specific bone changes that indicate the need for parathyroidectomy have not been clearly established. There are virtually no prospective data that evaluate decisions to operate based upon bone mass measurements nor randomized clinical trials comparing the outcome of surgically treated patients with those who have not had surgery. Based on the literature, bone mass measurements cannot predict who among asymptomatic patients will require parathyroidectomy. There is some evidence that nonsurgically treated patients and those who remained hypercalcemic after unsuccessful surgery lost bone at the same percentage rate as normal control subjects.