Background: Hypertension is a very common and important disease. There are conflicting reports about mercury, a trace element, in the genesis of hypertension.

Methods: In this study we examined the relationship between blood mercury levels and hypertension prevalence in a population-based sample of hypertensive and normotensive patients at the Shariati Hospital and the Tehran Heart Center in Tehran, Iran. A cross sectional sampling of 224 patients, aged 40-80 years, who participated in physical examinations conducted in 2006 were included in this study. The population that participated in this study were sample of hypertensive (n=112) which had essential hypertension and normotensive (n=112) patients which had no history of essential hypertension at the Shariati Hospital and the Tehran Heart Center in Tehran. The consent of all the patients were taken in the written form before the experiments. After selecting the patients the range of blood mercury levels were measured with Flame atomic absorption.

Results: The range of blood mercury levels was 0 to 39.55 µg/dL. The mean blood mercury level of hypertensive patients (10.75 +1.23 µg/dL) was higher than that of normotensive patients (1.6 +1.02 µg/dL). There was a significant difference in the mean blood mercury level of normotensive men (1.74 +1.56 µg/dL) versus that of hypertensive men (11.9 +1.38 µg/dL). The mean blood mercury level of normotensive women (1.5 µg/dL) was also significantly different from that of hypertensive women (9.65 +0.53 µg/dL) (p<0.001).

Conclusions: In this population, there is a positive relationship between the concentration of blood mercury levels and the presence of hypertension.