Does sodium sensitivity affect nocturnal blood pressure variation in outpatients with hypertension?

We investigated the relationship between sodium sensitivity and diurnal variation of blood pressure in outpatients with hypertension. Twenty hypertensives were maintained on both a regular sodium diet for a period of 2 weeks and a low salt (7 g/day) diet for a period of one or two weeks. Ambulatory blood pressure was recorded at thirty minute intervals for 24 hours by automatic device before and during low salt diet. Patients were classified by nocturnal fall in blood pressure. 14 patients were classified as sodium sensitive, whereas 6 were classified as non-sodium sensitive on the basis of a > or = 0 in salt sensitive index caused by sodium restriction. Incidence of reversed dipper and non-dipper in systolic blood pressure was reduced by sodium restriction, however, dipper and extreme dipper were increased. In conclusion, the results of this study show that patients with high sodium sensitivity index have strong sodium sensitivity and non-dipper is not always changed by sodium restriction.