Twenty-four-hour urinary sodium and potassium excretion and associated factors in Japanese secondary school students

Abstract

20-h collecting period and no missed voiding. The 24-h sodium excretion was 163.2±36.8 and 149.8±45.1 mmol per 24 h for the boys and girls, respectively. Considering daily habits and loss from sweat, intake was assumed to be 10.6±1.2 and 10.0±2.4 g per day for the boys and girls, respectively. The 24-h potassium excretion was 43.4±10.8 and 45.8±14.4 mmol per 24 h for the boys and girls, respectively. Estimated usual potassium intake was 2195±401 and 2330±630 mg per day for the boys and girls, respectively. Sodium excretion was associated with sodium and potassium concentrations in overnight urine samples and physical activity. Potassium excretion was associated with height and physical activity. We described daily sodium and potassium excretion in Japanese secondary schoolchildren. Excretion was associated more with physical activity than with bodyweight. Therefore, the estimation methods used in adults are not applicable for use in adolescents.