Simple blood test improves outcomes for resistant hypertension

Doing a blood test before prescribing treatment for hypertension improves treatment for patients with resistant high blood pressure, a new study has shown. The tests help to identify the cause, leading to the prescription of a more accurate regimen to lower blood pressure.

The blood tests measure the levels of plasma renin, a protein secreted by the kidneys and levels of adolsterone, a hormone that causes salt and water retention, leading to identification of the physiological changes causing the hard-to-treat hypertension.

Low levels of both renin and aldosterone often cause salt and water retention due to mutations affecting kidney tubules. For the study, 94 patients with hypertension in Kenya, Nigeria and South Africa were treated for hypertension. Forty-two of them were treated with the usual course of treatment, while 52 first took blood tests, then treatment was prescribed based on the results of the tests.

In the first group which was treated without taking blood tests, 11.1 per cent had controlled blood pressure after one year.  In the second group whose blood test results were used to determine treatment, 50 per cent had controlled blood pressure after a year. Patients with  high levels of plasma renin and adolsterone respond to amiloride medication.

“If a patient has salt and water retention, it causes high blood pressure and also feeds back and shuts down both renin and aldosterone,” said Dr David Spence, the lead researcher of the study published in the American Journal of Hypertension. The researchers hope that their findings will inform guidelines for the treatment of resistant hypertension, especially among Africans, leading to more accurate therapy.