Racial Disparities in Fluid Intake and Plasma Copeptin in Young Adults
Authors: Stute Nina Lawrene , Linder Braxton A. , Sanchez Sofia , Hutchison Zach , Tharpe McKenna , Vondrasek Joseph D. , Munoz Colleen 
Published: May 2024

INTRO: Underhydration, or habitual low water intake, is associated with increased plasma copeptin, a surrogate marker of arginine vasopressin. Importantly, plasma copeptin is associated with development of cardiovascular disease (CVD) and chronic kidney disease (CKD). Compared with White individuals, Black individuals are more likely to be underhydrated, to develop CVD and end-stage CKD, and exhibit higher plasma copeptin in middle-age and older adulthood. However, there is limited information on potential racial differences in plasma copeptin in young apparently healthy adults, which may have implications for incident CVD and CKD. Therefore, we sought to determine whether young Black adults reported lower fluid intake and exhibited higher plasma copeptin concentration when compared with young White adults. Methods: We analyzed pre-existing data from two registered clinical trials (NCTs 04576338 and 05132556). Participants (n=86, sex; 40F/46M, race; White n=48, Black n=38, age; 21±2 years, BMI; 25±4 kg/m2) completed a three-day food and fluid log and underwent a venous blood draw to measure plasma copeptin concentration (BRAHMS Copeptin proAVP KRYPTOR). Food and fluid records were analyzed using the Nutrition Data System for Research for % fluid from food or water. Separately, records were used to operationalize beverage intake into 8 categories (water, sugar-sweetened beverages (SSB), milk/non-dairy alternatives, 100% juice, non-caloric beverages, plain coffee or tea, milk/sugar added coffee or tea, and alcohol). Statistical analyses included Mann-Whitney U tests for fluid intake data and ANCOVA for plasma copeptin concentration (controlled for site). Plasma copeptin was log transformed. Additionally, we assessed relations between fluid intakes and plasma copeptin concentration using Spearman’s (ρ) correlations. We set α at ≤ 0.05. Results: Compared with White adults, Black adults consumed less total fluid (Black; 1981 ±1035 vs. White; 2780±1242mL), water, alcohol, and coffee/tea (plain and milk/sugar-added), but more juice (all p’s<0.05). There were no differences in % fluid from food or water, milk/non-dairy alternatives, non-caloric beverages, or SSBs. Black individuals exhibited ~22% higher plasma copeptin concentration (Black; 5.5±2.8 vs. White; 4.5±2.8pmol/L, ANCOVA p=0.022). Irrespective of race, copeptin was negatively correlated with water intake (ρ=-0.230, p=0.034). CONCLUSION: Black young adults reported a significantly lower fluid intake and exhibited higher plasma copeptin concentration when compared with White young adults. Future studies should attempt to address racial disparities in hydration practices, which may attenuate racial differences in copeptin and corresponding health disparities. NIH-K01HL147998 (ATR), Auburn University Offce of Vice President for Research Support Program (ATR). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.