Introduction: Echocardiographic studies in patients with primary hyperparathyroidism (PHPT) suggest that up to half of patients have left ventricular dysfunction and an increased risk of congestive heart failure that improve after parathyroidectomy. The cardiac hormone B-type natriuretic peptide (BNP) is an independent risk marker for heart failure.
Methods: Prospective cohort study of consecutive unselected patients with biochemical diagnosis of PHPT. Plasma BNP levels were measured preoperatively and at 3-months after parathyroidectomy using chemiluminescent immunoassay (Bayer Centaur analyser).
Results: Between Nov 2005 and April 2006, 76 patients were diagnosed with PHPT (17M:59F, aged 2789 years). After adjustment for age, there was a positive correlation between PTH/hypercalcaemia and BNP levels (r=0.8, P<0.001). Patients whose BNP levels were higher than the age-related 95% percentile had equally raised calcium and PTH levels but were more likely to use beta-blockers or ACE inhibitors (Table).
|N||BNP (pmol/l)||Calcium (mmol/l)||PTH (pmol/l)||On β-blockers||On ACE inhibitors|
|19 (25%)||59.9±62.2 (15.2275.3)||2.82±0.25||22.5±15.8||7/19||6/19|
|57 (75%)||5.62±3.77 (0.613.8)||2.91+0.23||18.3±12.2||5/57||6/57|
To date, 30 patients had parathyroidectomy and were found to have a single parathyroid adenoma. At 3-months follow-up all were normocalcaemic and had no significant change in BNP levels (10.6±11.6 vs. 10.1±11.3, P=NS paired t-test).
Conclusion: BNP levels in patients with PHPT reveal a lower incidence of heart failure than suggested by echocardiographic studies. The positive correlation between PTH and BNP levels supports the hypothesis that high PTH levels have detrimental effects on myocardial function. At 3-months after parathyroidectomy there is no significant change in BNP levels.