Management of Mild Primary Hyperparathyroidism

Abstract

Primary Hyperparathyroidism (PHPT) is a common endocrine disorder characterized by elevated calcium levels and inappropriately high parathyroid hormone (PTH) levels. Mild PHPT, without apparent symptoms or signs, is now the predominant form, probably due to an increase in measurements of both calcium and PTH. The overall aim of this thesis was to investigate if surgical removal of the parathyroid adenoma had an effect on long-term mortality and morbidity in mild PHPT. In the Scandinavian Study of Primary Hyperparathyroidism (SIPH-study), we followed 191 patients, of whom 95 were randomized to parathyroidectomy (PTX), and 96 were randomized to observation (OBS). Both groups were followed with annual visits over a period of 10 years. The study's primary end-point was mortality. The mortality was equal in both groups after ten years and after an extended follow-up period of up to twenty years. We further investigated the incidence of cardiovascular and cerebrovascular events, fractures, malignancies, and kidney stones during the ten years of follow-up. There were no statistical differences between the groups for these secondary outcomes. Patient reported outcomes on quality of life indicated a subtle improvement in the PTX group. However, this improvement was weaker than what is generally accepted to be clinically relevant. Lastly, we investigated the effect of PTX on bone mineral density with dual-energy X-ray absorptiometry (DXA). Here, we found a significant treatment effect in all the measured DXA compartments in favor of the PTX group. The OBS group had a significant decrease in all compartments compared to baseline. However, this difference did not transfer to an increased fracture risk over ten years. In summary, mild PHPT seems to be a stable disease, and PTX does not appear to reduce mortality or morbidity over the course of a decade. Observation of patients with mild PHPT seems safe in a 10-year perspective.