Low testosterone and hyperkinetic blood pressure responses in a cohort of South African men: the SABPA study

Abstract

Hypertension (HT) and the metabolic syndrome are major problems in Africa. The role of sex hormones in the cardiovascular profile of black Africans in South Africa has not been studied. Our objective was to study the association between the sex hormones and ambulatory blood pressure and the heart rate (HR) in black and white South Africans. The 24-hour ambulatory blood pressure measurements were performed and the blood samples were taken between 07:00 and 09:00 hours. A total of 80 black and 98 white South African teachers between 25 and 65 years of age from similar socioeconomic backgrounds from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study were included. As a result, a more vulnerable cardiovascular profile was observed in Africans compared with Caucasians. In the African group, low testosterone (T) explained 19%–36% of the variance in systolic blood pressure (SBP), diastolic blood pressure (DBP), and HR, whereas in the Caucasian group non-sex-hormone-binding globulin (non-SHBG)-bound T explained 27% of the variance in HR. In the African males, inverse associations between blood pressure and T (SBP: P = .08; DBP: P = .02) and non-SHBG-bound T (SBP: P < .001; DBP: P < .01) and HR (P < 0.01) were observed. Ambulatory HR predicted a prediabetic state in Africans. In conclusion, low T levels may predispose or result in impaired cardiovascular function in African men. The possibility exists that a prediabetic state, vagal-impaired HR, and hyperkinetic blood pressure responses may predispose or result in low T levels in African men