The association between salt sensitivity of blood pressure and family history of hypertension.

1. The salt sensitivity index (SSI) and family history of hypertension were studied in 140 hospitalized patients with essential hypertension to clarify whether salt sensitivity of blood pressure is related to familial disposition to hypertension. 2. SSI was calculated by dividing the change of mean blood pressure by that of urinary sodium excretion when salt intake was restricted from 15 to less than 3 g/day. 3. Family history of hypertension was classified into three groups depending on the presence or absence of hypertension in the father, mother and siblings. 4. The group without a family history of hypertension showed a significantly lower SSI value than other groups. 5. In multiple regression analysis undertaken within each gender, SSI showed significant partial correlations with blood pressure and family history of hypertension in the female group (r = 0.402 and 0.265, respectively), whereas in the male group it showed a positive correlation only with blood pressure (r = 0.501). These results indicate that salt sensitivity of blood pressure is related to familial disposition to hypertension. This association was more apparent in the female than male group and its gender difference can be partially attributed to the fact that blood pressure in the female group is more sensitive to salt.