Assessment of dietary intake and urinary excretion of sodium and potassium in adults

Abstract

Hypertension is associated with elevated sodium and low potassium intakes. The determination of sodium and potassium intake by dietary records is inaccurate, being its measurement from 24-h urine collection the reference method. To determine urinary sodium and potassium excretion in adults. To compare dietary sodium and potassium intake and their excretion from an isolated urine sample against the reference method. Seventy healthy adults aged 35 ± 8 years with a body mass index 25 ± 2 kg/m² (36 women) were studied. Urine was collected over 24 h, including an isolated urine sample taken in fasting conditions. Additionally, three 24-h dietary records were performed. Reported sodium and potassium intake was 2,720 ± 567 and 1,068 ± 433 mg/day, respectively. In turn, urinary excretion of sodium and potassium was 4,770 ± 1,532 and 1,852 ± 559 mg/day, respectively. These latter values were significantly higher than those obtained by dietary records. Furthermore, the urinary sodium and potassium excretion estimated from an isolated urine sample was 4,839 ± 1,355 and 1,845 ± 494 mg/day, respectively. These values were similar to those obtained with a 24 h urine collection. Dietary records underestimated electrolyte intake when compared with the reference method. Using an isolated urine sample to estimate electrolyte intake may be a reliable alternative.