Use of Urine Biomarkers to Assess Sodium Intake: Challenges and Opportunities

Abstract

This article summarizes current data and approaches to assess sodium intake in individuals and populations. A review of the literature on sodium excretion and intake estimation supports the continued use of 24-h urine collections for assessing population and individual sodium intake. Since 2000, 29 studies used urine biomarkers to estimate population sodium intake, primarily among adults. More than half used 24-h urine; the rest used a spot/casual, overnight, or 12-h specimen. Associations between individual sodium intake and health outcomes were investigated in 13 prospective cohort studies published since 2000. Only three included an indicator of long-term individual sodium intake, i.e., multiple 24-h urine specimens collected several days apart. Although not insurmountable, logistic challenges of 24-h urine collection remain a barrier for research on the relationship of sodium intake and chronic disease. Newer approaches, including modeling based on shorter collections, offer promise for estimating population sodium intake in some groups.

Keywords: 24 h; balance; metabolism; overnight; spot; sweat.

Figure 1

Mean 24-h sodium excretion based on 24-h urine collection (measured), and spot urine sodium concentration used to estimate 24-h sodium excretion based on prediction equations (74), for 339 adults (50% black race-ethnicity) aged 18–39 years living in the United States (25), 98 adults aged 18–65 years living in New Zealand (103), and 448 adults aged 35–70 years from 11 diverse countries in South America, Africa, India, East Asia, and the Middle East (105).