Early parathyroidectomy in mild primary hyperparathyroidism: Effects on heart and bones

Sammanfattning: There is an ongoing controversy regarding how to take care of patients with mild primary hyperparathyroidism (PHPT). Some recommend surgical treatment at diagnosis, others just follow-up as long as there is no evidence of disease progression. The aim of this thesis was to evaluate cardiac and skeletal risk factors related to the duration of mild PHPT. Fifty patients with mild PHPT were randomized to parathyroidectomy (PTX) either at diagnosis or 1 year later. The skeleton was examined using dual-energy X-ray absorptiometry and biochemical markers. Echocardiography, equilibrium radionuclide angiography (ERNA) and plasma NT-proBNP were used to evaluate cardiac structure and function. Whereas bone mineral density (BMD) in the lumbar spine increased equally after PTX in both groups of patients, the group with an extra year of exposure to mild PHPT showed impaired ability to regain BMD in the hip. Surprisingly, the most important determinant of the increase in BMD after PTX in postmenopausal women was not the normalized serum level of parathyroid hormone or calcium, but a concomitant increase in circulating bioavailable testosterone. At baseline, myocardial hypertrophy (a strong risk factor of premature death) was correlated to the serum concentration of parathyroid hormone but not to the level of serum calcium. At the end of the study, the patients who had delayed PTX showed significant increase of left ventricular hypertrophy, in contrast to the group treated immediately. After PTX, a transient dip occurred in heart function parameters measured by ERNA. This dip was subclinical and had no influence on exercise capacity. Abnormal cardiac secretion of NT-proBNP substantiated the observations made by ERNA. In conclusion, these results obtained by a prospective and randomized study design, show that early PTX has favourable effects on heart and bones in patients with mild PHPT. Thus, PHPT should be treated surgically without delay irrespective of serum calcium level.