High salt intake promotes a decline in renal function in hypertensive patients: a 10-year observational study.
We investigated the influence of long-term salt load on renal function in hypertensive patients. The subjects were 133 hypertensive patients (80 women and 53 men, mean age 60±9 years) who underwent at least five successful 24 h home urine collections during the 10-year observation period. Blood pressure (BP) and 24-h urinary salt and creatinine excretion levels were measured. BP decreased from 143±12/85±8 to 129±14/68±11 mm Hg during the 10.5-year observation period, and this decrease was associated with patients taking an increased number of antihypertensive drugs (1.3±1.0 to 2.2±1.1). The estimated glomerular filtration rate (eGFR) also significantly decreased from 71.7±14.6 to 64.7±16.5 ml min(-1) (P<0.01), and the change in eGFR was -0.68 ml min(-1) per year on average. The average salt excretion was 8.6±2.2 g per day and showed a significant negative correlation with the change in eGFR (r=-0.21, P=0.02). Subjects with an average salt excretion<8 g per day showed a significantly slower decline in renal function than those with an average salt excretion 8 g per day (the change in eGFR: -0.41±1.10 vs. -0.83±1.19 ml min(-1) per year, P<0.05). In the multivariate analysis, the average salt excretion (partial r=-0.19, P=0.03) and baseline eGFR (partial r=-0.23, P=0.01) were significantly associated with the change in eGFR. This association was independent of BP change or an increased number of antihypertensive drugs. The results suggest that long-term salt load promotes a decline in renal function in hypertensive patients; thus, salt restriction is encouraged, to prevent renal damage.
Department of Internal Medicine, Fukuoka Dental College Medical and Dental Hospital, Fukuoka, Japan. ota.yuko.hp@mail.ncvc.go.jp
Yuko
Y
Ohta
Takuya
T
Tsuchihashi
Kanako
K
Kiyohara
Hideyuki
H
Oniki
D000368:Aged; D000959:Antihypertensive Agents / Q000494:pharmacology / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D003404:Creatinine / Q000652:urine; D004305:Dose-Response Relationship, Drug; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology*; D007668:Kidney / Q000187:drug effects* / Q000503:physiopathology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012965:Sodium Chloride / Q000652:urine; D017673:Sodium Chloride, Dietary / Q000494:pharmacology*; D013997:Time Factors
D000959:Antihypertensive Agents; D017673:Sodium Chloride, Dietary; D012965:Sodium Chloride; D003404:Creatinine