POPULATION-BASED SURVEY OF HUMAN SODIUM AND POTASSIUM EXCRETION

1. During the 1989 National Heart Foundation Risk Factor Prevalence Survey a subsample in Hobart collected 24 h urine samples to measure electrolyte excretion. 2. The ranges were 30-344 mmol/24 h for Na+ excretion (mean 160 mmol/24 h for men, 124 mmol/24 h for women), and 25-119 mmol/24 h for K+ excretion (mean 77 mmol/24 h for men, 68 mmol/24 h for women). 3. As in other surveys, women excreted about 20-25% less Na+ and K+ than men, although there was no significant sex difference in the ratio of Na+/K+ excretion. 4. The recommended dietary intake (RDI) for Na+ and K+ was followed simultaneously by 19% of subjects, and 13% had a 24 h urinary Na+/ K+ ratio less-than-or-equal-to 1.0. 5. Observance of the RDI limited the value of iodized salt for goitre prophylaxis. 6. Sodium excretion rates were outside the therapeutic range of thiazide diuretics in 22% of subjects. 7. Diet groups for long-term prospective cohort studies to test the prophylactic value of avoiding salt could apparently be recruited from existing subsamples of the population.