Sodium-lithium countertransport in erythrocytes of hypertension prone families in Utah.

Sodium-lithium countertransport was measured in July 1980-December 1982 in 841 persons from 48 Utah families prone to hypertension. Mean countertransport in 54 hypertensive adults (0.32 +/- 0.01 standard error of the mean) was significantly higher than in 511 normotensive adults (0.26 +/- 0.005, p less than 0.001) but with much overlap between the two groups. This difference was observed in both men and women. Only 26% of the subjects with essential hypertension had values above 0.40 (considered "high" by most other published reports). High values were seen in only 2% of 276 youths under age 18 years in contrast to 11% of the normotensive adults (p less than 0.001). Among normotensive adults, countertransport was higher in men than women, and correlated with weight, diastolic blood pressure, and age (all significant at p less than 0.01). None of these findings were seen in youths. In multivariate analyses, only weight continued to be significantly correlated with countertransport. The difference between countertransport levels in hypertensive vs. normotensive adults remained significant even after adjusting for weight. While confirming other reports of higher mean sodium-lithium countertransport in persons with essential hypertension, this study shows much overlap of values between groups and potential confounding effects of weight. When the authors compared their results with studies that show little overlap between hypertensive and normotensive adults, they found that the data for the normotensive adults in this study are similar to those reported in the other studies, but that the hypertensive adults include a larger percentage of individuals with low countertransport values.