Context: Mild primary hyperparathyroidism (PHPT) is a common disease especially in middle-aged and elderly women. The diagnosis is frequently made incidentally and treatment strategies are widely discussed.
Objective: To study the effect of parathyroidectomy (PTX) compared with observation (OBS) on biochemistry, safety, bone mineral density (BMD), and new fractures.
Design: Prospective, randomized controlled study (SIPH study), with a 5-year follow-up.
Setting: The study was conducted at multicenter, tertiary referral centers.
Patients: Of 191 randomized patients with mild PHPT, biochemical data were available for 145 patients after 5 years, with a mean age at inclusion of 62.8 years (OBS group, 9 males) and 62.1 years (PTX group, 10 males).
Intervention: Parathyroidectomy vs observation.
Main outcome measures: Biochemistry, BMD, and new radiographic vertebral fractures.
Results: Serum-calcium and PTH-levels normalized after surgery and did not deteriorate by observation. BMD Z-scores were normal at inclusion in the lumbar spine (LS) and femoral neck (FN). For LS, BMD Z-scores were stable for 5 years with observation, but decreased in FN (P < .02). After surgery, BMD Z-scores increased significantly in both compartments (P < .02 for both), with a highly significant treatment effect of surgery compared to observation (P < .001). During follow-up, five new clinically unrecognized vertebral fractures were found in 5 females, all in the OBS group (P = .058).
Conclusion: Even though new vertebral fractures occurred only in the observation group, the frequency was not significantly different from the surgery group. Longer follow-up is needed before firm conclusions can be drawn about the long-term safety of observation, as opposed to surgery.
Trial registration: ClinicalTrials.gov NCT00522028.