Clinical and Experimental Pharmacology and Physiology (1992) 19,327-330
SHORT COMMUNICATION
POPULATION-BASED SURVEY OF HUMAN SODIUM AND POTASSIUM EXCRETION T. C. Beard, R. Eickhoff, Z. A. Mejglo,* M. Jones, S. A. Bennett' and T. Dwyer Menzies Centrefor Population Health Research, *Repatriation General Hospital, Hobart, Tasmania, and 'Australian Institute of Health, Canberra, Australian Capital Territory, Australia (Received 13 December 1991)
SUMMARY 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 mmo1/24 h for Na+ excretion (mean 160 mmo1/24 h for men, 124 ' excretion (mean 77 mmo1/24 h for men, 68 mmol/24 h for women), and 25-1 19 mmol/24 h for K 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 5 1.O. 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. Key words: potassium excretion, recommended dietary intake, sodium excretion.
INTRODUCTION In 1988 the National Better Health Program adopted a sodium excretion rate of 100 mmol/day or less as a dietary target for the whole Australian population by the year 2000 (Health Targets and Implementation [Health for All] Committee 1988). At that time there were no published baseline data on 24 h electrolyte
excretion rates based on a random sample of the adult population, and the 1989 Risk Factor Prevalence Survey conducted by the National Heart Foundation of Australia (NHFA) provided an opportunity to collect data for Hobart, Tasmania.
Correspondence: Dr T. C. Beard, Menzies Centre, 43 Collins Street, Hobart, Tasmania 7000, Australia. Presented at the High Blood Pressure Research Council of Australia meeting on 12-13 December 1991, Adelaide, Australia.
T. C. Beard et al.
328
METHODS The NHFA selected a probability sample of 1500 people, aged 20-69 on 30 June 1989, from the Commonwealth electoral roll for Hobart, and invited them in random order to attend the NHFA centre for interview. Respondents answered a questionnaire, had their height, weight and blood pressure recorded and a blood sample taken. Of the 1084 respondents, the last 41 1 received a written invitation, which made no reference to salt or sodium, to contact the Menzies Clinic for a urine test. Those who complied received a container and written and verbal information about collecting and delivering a 24 h urine sample after giving informed consent that again made no mention of salt or sodium. On delivery of the urine sample they answered a checklist on sodium intake (Millar & Beard 1988). Samples received were measured for volume and analysed for sodium and potassium in a Beckman ASTRA analyser using ion-specific electrodes, and for creatinine using the Jafftt-rate reaction. Ethical approval was given by the Ethics Committee of the University of Tasmania.
RESULTS Of 56 persons who contacted the Menzies Clinic, 54 (22 men and 32 women) provided 24 h urine samples. The mean ages were 50 years for men and 48 years for women, and the range for both sexes was 24-69 years. Based on volume, K+and creatinine content, all
/
samples were considered to be complete. Data for one woman, who was breast feeding a 7 month old baby, were adjusted upwards by 5 mmol of sodium and 12 mmol of potassium to allow for the electrolyte content of 900 mL of breast milk.
Excretion ranges The range of Na+ excretion was 30-344 mmol, and the mean was 160 mmol for men and 124 mmol for women. The range for K was 25-1 19 mmol (mean 77 mmol for men and 68 mmol for women). The sodium target of the Better Health Program ( N a + I100 mmol/24 h) was met by 14 people (26% of the sample), of whom 10 (19%) lay within the range of the recommended dietary intake (RDI) for both sodium (Bullock 1982; Beard 1990a) and potassium (Truswell 1982, 1990). Seven people (13% of the sample) had a 24 h urinary Na+/K+ ratio of 5 1.0. Twelve people (22%) had Na+ excretion rates that were either
SHORT COMMUNICATION
POPULATION-BASED SURVEY OF HUMAN SODIUM AND POTASSIUM EXCRETION T. C. Beard, R. Eickhoff, Z. A. Mejglo,* M. Jones, S. A. Bennett' and T. Dwyer Menzies Centrefor Population Health Research, *Repatriation General Hospital, Hobart, Tasmania, and 'Australian Institute of Health, Canberra, Australian Capital Territory, Australia (Received 13 December 1991)
SUMMARY 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 mmo1/24 h for Na+ excretion (mean 160 mmo1/24 h for men, 124 ' excretion (mean 77 mmo1/24 h for men, 68 mmol/24 h for women), and 25-1 19 mmol/24 h for K 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 5 1.O. 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. Key words: potassium excretion, recommended dietary intake, sodium excretion.
INTRODUCTION In 1988 the National Better Health Program adopted a sodium excretion rate of 100 mmol/day or less as a dietary target for the whole Australian population by the year 2000 (Health Targets and Implementation [Health for All] Committee 1988). At that time there were no published baseline data on 24 h electrolyte
excretion rates based on a random sample of the adult population, and the 1989 Risk Factor Prevalence Survey conducted by the National Heart Foundation of Australia (NHFA) provided an opportunity to collect data for Hobart, Tasmania.
Correspondence: Dr T. C. Beard, Menzies Centre, 43 Collins Street, Hobart, Tasmania 7000, Australia. Presented at the High Blood Pressure Research Council of Australia meeting on 12-13 December 1991, Adelaide, Australia.
T. C. Beard et al.
328
METHODS The NHFA selected a probability sample of 1500 people, aged 20-69 on 30 June 1989, from the Commonwealth electoral roll for Hobart, and invited them in random order to attend the NHFA centre for interview. Respondents answered a questionnaire, had their height, weight and blood pressure recorded and a blood sample taken. Of the 1084 respondents, the last 41 1 received a written invitation, which made no reference to salt or sodium, to contact the Menzies Clinic for a urine test. Those who complied received a container and written and verbal information about collecting and delivering a 24 h urine sample after giving informed consent that again made no mention of salt or sodium. On delivery of the urine sample they answered a checklist on sodium intake (Millar & Beard 1988). Samples received were measured for volume and analysed for sodium and potassium in a Beckman ASTRA analyser using ion-specific electrodes, and for creatinine using the Jafftt-rate reaction. Ethical approval was given by the Ethics Committee of the University of Tasmania.
RESULTS Of 56 persons who contacted the Menzies Clinic, 54 (22 men and 32 women) provided 24 h urine samples. The mean ages were 50 years for men and 48 years for women, and the range for both sexes was 24-69 years. Based on volume, K+and creatinine content, all
/
samples were considered to be complete. Data for one woman, who was breast feeding a 7 month old baby, were adjusted upwards by 5 mmol of sodium and 12 mmol of potassium to allow for the electrolyte content of 900 mL of breast milk.
Excretion ranges The range of Na+ excretion was 30-344 mmol, and the mean was 160 mmol for men and 124 mmol for women. The range for K was 25-1 19 mmol (mean 77 mmol for men and 68 mmol for women). The sodium target of the Better Health Program ( N a + I100 mmol/24 h) was met by 14 people (26% of the sample), of whom 10 (19%) lay within the range of the recommended dietary intake (RDI) for both sodium (Bullock 1982; Beard 1990a) and potassium (Truswell 1982, 1990). Seven people (13% of the sample) had a 24 h urinary Na+/K+ ratio of 5 1.0. Twelve people (22%) had Na+ excretion rates that were either
![[Relationship between urinary sodium and potassium excretion and blood pressure].](/assets/img/hold.png)
