Simple Blood Tests Improve Hypertension Treatment

African and African American hypertensives tend to retain salt and water, with lower levels of plasma renin and more resistant hypertension. Two simple blood tests were able to drastically improve treatment for resistant hypertension across three sites in Nigeria, Kenya and South Africa.

By testing patients' levels of plasma renin, a protein secreted by the kidneys, in combination with levels of aldosterone, a hormone that causes salt and water retention, physicians were able to identify the physiological changes causing the hypertension. This led to personalized and more accurate therapy.

An international team of scientists under the auspices of Western University enrolled patients at hypertension clinics in Nigeria, Kenya, and South Africa with a systolic blood pressure greater than140 mm Hg or diastolic pressure greater than 90 mm Hg despite treatment were allocated to usual care (UC) versus physiologically individualized care (PhysRx). Plasma renin activity and aldosterone were measured using enzyme-linked immunosorbent assay (ELISA) kits. Patients were followed for one year; the primary outcome was the percentage of patients achieving blood pressure less than140 mm Hg and diastolic less than 90 mm Hg.

Of the 94 patients who completed the study, 42 were treated with the usual course of treatment, 52 were given the blood tests, and treatment was decided based on the results. In the group who were given usual treatment, 11.1% had controlled blood pressure after one year, versus 50% in the group that received the blood test. Systolic control was achieved in 13.9% of UC versus 60.3% of PhysRx; diastolic control in 36.1% of UC versus 67.2% of PhysRx.

The authors concluded that physiologically individualized therapy based on renin/aldosterone phenotyping significantly improved blood pressure control in a sample of African patients with uncontrolled hypertension. This approach should be tested in African American and other patients with resistant hypertension. J. David Spence, MBA, MD, FRCPC, a professor and lead investigator of the study said, “"If a patient has salt and water retention, it causes high blood pressure and also feeds back and shuts down both renin and aldosterone.” The study was published on May 2, 2017, in the American Journal of Hypertension.