Shailendra Sharma, MD, and colleagues at the University of Colorado in Denver performed two analyses of 2001-2006 data from 13,917 individuals aged 18 years or older (mean age 45 years) who participated in the National Health and Nutrition Examination Survey. Investigators evaluated dietary sodium and potassium intake from 24-hour dietary recall obtained by trained interviewers. They classified subjects into quartiles of salt intake (2,116 mg/day or less and 2117-3,061, 3,062-4,267, and more than 4,267 mg/day) and quartiles of potassium intake (1,737 mg/day or less and 1,738-2,455, 2,456-3,341, and 3,342 or more mg/day). The also classified subjects low, normal, and high potassium intake (less than 2,000, 2,000-4,000, and more than 4,000 mg/day).
The mean sodium intake was 3,520 mg/day and the mean potassium intake was 2,760 mg/day. The mean estimated glomerular filtration rate (eGFR) was 88 mL/min/1.73 m2.
CKD, defined as an eGFR below 60 mL/min/1.73 m2, was present in 14.2% of the study cohort. After adjusting for age, gender, race, diabetes and hypertension status, and diuretic usage, Dr. Sharma’s group found a significant association between higher quartiles of sodium intake and decreased likelihood of CKD. Compared with participants in the first quartile, those in the third and fourth quartiles had a significant 23% and 34% decreased likelihood of CKD.
Low potassium levels were associated with a significant 35% increased risk of CKD compared with normal intake. High potassium intake was associated with a 22% reduced risk, but this association was of borderline significance. Individuals in the first quartile of potassium intake had a significant 55% increased risk of CKD compared with those in the fourth quartile.