Racial difference in salivary sodium-potassium ratio in low renin essential hypertension

We have studied the relationship between plasma renin activity (PRA) and the salivary sodium-potassium (Na-K) ratio, an index of mineralocorticoid effect, in 223 patients with essential hypertension. In 24 white patients with low PRA, the median Na-K ratio was 0.74, which was significantly lower than the ratio of 1.40 in 54 normal white subjects and the ratio of 1.10 in 34 white hypertensive patients with normal PRA. The Na-K ratio in 71 black patients with low PRA was 1.06, which was not significantly lower than the ratio of 1.50 in 38 black normal subjects or the ratio of 1.56 in 94 black hypertensive patients with normal PRA. These findings indicate a difference in salivary Na-K ratios between white and black patients with low renin essential hypertension and suggest a racial difference in the pathophysiology of this form of hypertension.