Reliability of salt-sensitivity testing in normotensive subjects.

We examined the reliability of dietary salt-sensitivity testing by repeatedly studying the effects of a high (220 mmol/day) and low (20 mmol/day) salt diet in 15 normotensive subjects. Reliability of classification of salt-sensitivity as described by the kappa statistic was 0.87 implying an almost perfect strength of agreement between the two parts of the study. Whereas only 20% of the subjects with negative familial histories of hypertension were salt-sensitive, this was the case with 68% of the subjects with positive familial histories. Our results show that salt-sensitivity can be reliably tested in normotensive subjects and that it is related to a familial history of hypertension.