 Statistical Methods The effects of sodium restriction and HCTZ on clinical and biological markers were first evaluated by Friedmans tests. If a global time-effect was significant, the change between baseline and the last measurement of the treatment period was tested by a Wilcoxons paired test. All data are expressed as median range minimum; maximum, except otherwise specified. Values of 24h-urine collection of each period used for analyses were mean of the measurements made on the two consecutive daily collections. Values for a given 24-h collection were excluded from analysis if the creatinine excretion on that collection varied by more than 15 or the sodium excretion varied by more than 25 from the mean of values for other collections by that patient. 