Increased plasma concentrations of N-terminal pro-B-type natriuretic peptide in patients with mild primary hyperparathyroidism

Objective Primary hyperparathyroidism (PHPT) is associated with heart disease. The aims of the present study were to evaluate how cardiac function and secretion of N-terminal pro-B-type natriuretic peptide (NT-proBNP) correlate in patients with mild PHPT, and how the plasma level of NT-proBNP is influenced by cure of the parathyroid disease. Design and patients Forty-two patients with PHPT without symptoms of heart disease were examined before and 1 year after curative parathyroidectomy. Measurements Plasma or serum concentrations of NT-proBNP, calcium, PTH, creatinine, oestradiol, testosterone and SHBG were measured. Cardiac function was evaluated by equilibrium radionuclide angiography (ERNA). Results At baseline, NT-proBNP levels correlated negatively with systolic function [left ventricular ejection fraction (LVEF), P < 0.001]. Twelve per cent of the patients had NT-proBNP levels above normal reference values preoperatively. One year postoperatively, the corresponding proportion was 21%. The mean plasma concentration of NT-proBNP increased after parathyroidectomy (P < 0.01) in parallel with a dip in diastolic function (peak filling rate, P < 0.05) and a falling trend in systolic function (LVEF, P = 0.08). The postoperative percentage changes in circulating NT-proBNP and total oestradiol correlated positively (P < 0.05). Conclusions Patients with mild PHPT and normal renal function may have high levels of circulating NT-proBNP despite the absence of symptomatic heart disease. Cure of the parathyroid disease is followed by a further increase in NT-proBNP secretion in parallel with ERNA measures, indicating subclinical changes in heart function. These results are in line with data indicating an association between PHPT and increased risk of premature death.