P1690Lab-on-a-chip based self-monitoring device for dietary intake of potassium and sodium: the LAB-CHIPS study

Abstract

Abstract Background Dietary sodium restriction and upholding adequate potassium intake is an important lifestyle modification strategy advocated in guidelines for the management of hypertension and for lowering cardiovascular risk in the general population. The gold standard for estimating sodium and potassium intake, 24-hour urine collection (24hUc), is time consuming and cumbersome, but most importantly not a good indicator of dietary habit due to day-to-day variation. New lab-on-a-chip technology has been developed to measure urinary sodium, potassium and creatinine excretion in a single drop of urine using microcapillary electrophoreses combined with conductivity analyses. Self-monitoring can be done at home over a longer period of time. Results are readily available. Purpose To assess agreement between 24hUc and the lab-on-a-chip self-monitoring device for estimating past 24h dietary sodium and potassium intake for single and multiple self-tests by using the Kawasaki, INTERSALT and Tanaka formulae. Methods Healthy participants (n=12) were asked to adhere to three different weekly dietary sodium restriction goals. Participants received verbal and written information to aim between 3.3 and 5.0 grams of sodium intake a day during week 1 (“normal”), >3.3<5.0 grams in week 2 (low) and >5.0 grams during week 3 (high). Weekly measurement instructions consisted of one self-test on day 1 through 6 and multiple self-tests (n=3) combined with a 24hUc on day 7. To estimate 24h sodium and potassium intake, Kawasaki, INTERSALT and Tanaka formulas were used. The Bland-Altman method was used to calculate the agreement. Results The agreement (mg/day) for sodium between 24hUc and a self-test on first morning urine (fmu) (Kawasaki), was −102±804 (normal), −860±592 (low) and 340±1406 (high). For multiple self-tests (n=3) performed on 24hUc days, using the INTERSALT formula, the agreement was: 577±832 (normal), −701±721 (low) and 1788±911 (high). Any combination of same day single or multiple INTERSALT or Tanaka self-tests and fmu Kawasaki did not result in better agreement. For potassium the agreement between 24hUc and fmu (Kawaksaki) was 1071±966 (normal), 1376±678 (low) and 1654±880 (high). Using the Tanaka formula resulted in further underestimation and thus worse agreement for same day self-tests and fmu. Conclusion In this study, agreement between 24hUc and the lab-on-a-chip self-monitoring device for estimating past 24h dietary sodium intake was best for a fmu self-test calculated with the Kawasaki formula. For estimating potassium intake, a fmu self-test with help of the Kawasaki formula overestimated potassium intake considerably. This lab-on-a-chip self-monitoring device has the potential to improve current lifestyle modification strategies.