Cardiac output in asymptomatic primary hyperparathyroidism: a stigma of early cardiovascular dysfunction?

The resting cardiac output pre- and postoperatively in 10 patients with asymptomatic primary hyperparathyroidism has been studied. All patients had normal renal function and arterial blood pressure without a previous history of cardiovascular disease. Ten normotensive patients with a non-toxic goitre awaiting thyroidectomy were studied as controls. The mean cardiac output of the hyperparathyroid patients was 7.2 l/minute (range 5.3-8.9) and of the control group 5.8 l/minute (range 5.2-6.3). Following a successful parathyroidectomy with return of the serum calcium to normal, the mean cardiac output was 6.3 l/minute (range 4.9-7.8) (p < 0.04). In 8 of the 10 patients there was a fall in the cardiac output following surgery; in 2 there was an increase. These results suggest that hyperparathyroid patients often have an elevated cardiac output which may fall following a successful parathyroidectomy.