Aims: A relation between left ventricular hypertrophy and parathyroid hormone (PTH) has been described in patients with end stage renal disease and secondary hyperparathyroidism. In vitro studies indicate a hypertrophic effect of PTH on cardiomyocytes. The purpose of this study was to examine the relation between PTH and left ventricular hypertrophy in a general population.
Methods and results: The fourth Tromsø study (1994-1995) included 27159 subjects. 2700 had serum PTH measurement and left ventricular mass by height (LVMH) estimated with M-mode echocardiography. Among these, 980 males and 1060 females were without known cardiovascular disease or valvular heart disease and did not use blood pressure medication. In this group, using a multiple linear regression model, body mass index (BMI), followed by systolic blood pressure, were found to be the strongest predictors of LVMH. In males older than 59 years and females younger than 60 years, PTH was a significant and positive predictor of LVMH (P<0.05). The relation between PTH and LVMH was not linear. There was a sharp increase in LVMH (both unadjusted and adjusted for age, BMI, and systolic blood pressure) in the upper PTH percentiles with the breaking point being the 95 percentile for men and the 98 percentile for women. Subjects in these upper PTH ranges had 12-17% higher adjusted LVMH than those in the lower 10% of the PTH range. This effect was not related to serum calcium level. If examining separately those with PTH levels within +/-2SD from the mean, no relation between PTH and LVMH was found.
Conclusions: PTH is an independent predictor of LVMH in males older than 59 years and females younger than 60 years. This effect is only seen when PTH is substantially elevated and may then be involved in cardiac pathophysiology.