In another study comprising 14 patients with mild to moderate HF, the renal and neurohormonal influences of tolvaptan were favorable in comparison with furosemide; both tolvaptan and furosemide raised urine volume, but tolvaptan preserved renal blood flow which was reduced by furosemide without influencing urine or serum sodium levels; there was no change in neurohormone levels in the tolvaptan group while furosemide raised renin and norepinephrine concentrations [38]. This evidence concerns the gene REN and hydrops fetalis.