The Comparison of Renal Handling of Sodium and Potassium According to Salt Intake between Control and Hypertensive Group

Kim, Keon Joong; Joo, Shin Bae; Kim, Yong Joon; Lee, Sang Min; Lee, Hong Soon; Lee, Hak Choong

Abstract

The salt-sensitivity has been generally accepted as a mechnism of high blood pressure in elderly hypertensive patients, and so it may result in a difference of renal handling of sodium and potassium between normal healthy control and elderly hypertensive patient. So to evaluate an lbove difference, the amount of 24 hours' urinary excretion of Na+ & K+ were measured in healthy normotensive control (10 case) and elderly hypertensive group(10 case) according to normal diet (12-15gm of NaCl) for first 3 days and low salt diet (3~5)gm of NaCi) for next 3 days, also blood rewwure was mintored. The results were followed : 1) 24 hours' urinary excretion of NA+ was increased in hypertensive group more than control group at first day of normal diet and low salt diet significantly. 2) After a replacement of normal diet to low salt diet, a maximal decrement of 24 hours' urinary excretion of Na+ was 25% at first day in control but 40% at second day in hypertensive group only. 3) There was a similar pattern of urinary excretion of K+ as Na+ in hypertensive group, but it was not stastically significant. 4) There was no significant changes of blood pressure, serum electrolyte and BUN/creatinine according to salt intake in both group. From above findings. We can conclude that a urinary excretion of sodium is delayed in elderly hypertensive group, and it is suggested that a delayed excretion of sodium. is associated with retention of sodium in body. So a persistent restriction of sodium is recommended in elderly hypertensive patient.