Association of Dietary Sodium and Potassium With Blood Pressure and Proteinuria in Africans With Kidney Disease

Introduction: Associations of dietary sodium (Na) and potassium (K) with blood pressure (BP) show conflicting results, with limited data in individuals of African ancestry. We examined cross-sectional associations of 24-hour urine Na (UNa24h) and K (UK24h), proxies for dietary intake, with BP and proteinuria in CKD cohorts in West Africa and USA. Methods: We analyzed participants in the Diet, CKD and ApolipoproteinL1 (DCA) study, an ancillary of the Human Hereditary and Health in Africa (H3Africa) Kidney Disease Study; and the Chronic Renal Insufficiency Cohort (CRIC) study. The exposures included calibrated UNa24h, UK24h and UNa24h-to-UK24h ratio. The outcomes were systolic and diastolic BP (SBP and DBP), and 24-hour urine protein at baseline. Using mixed-effect linear regression, we calculated crude and adjusted effect sizes (b coefficients) and 95% confidence intervals. Results: Median UK24h excretion was lowest in DCA (36, interquartile range: 28–48) compared with Black (45, interquartile range: 34–57 mmol/24 h) and non-Black CRIC participants, (63, interquartile range: 50–78 mmol/24 h) (all P < 0.001). Median UNa24h excretion was lowest in DCA participants. UK24h was associated with lower DBP (Q4 vs. Q1, −2.18 [−3.90 to 0.45]) in Black CRIC participants. The association of UK24h with DBP was directionally consistent but not significant in the DCA or non-Black CRIC participants. Higher quartiles of UNa24h and UNa24h/ UK24h were associated with higher DBP in non-Black CRIC participants. UNa24h was associated with higher proteinuria in all participants. Conclusion: The reasons for the differences in associations may arise from Na sensitivity, differences in UK24h excretions, and dietary Na-K imbalance. The implications of lower UK24h in African populations require future studies.

Duke Scholars

Author Rasheed Adebayo Gbadegesin Pediatrics, Nephrology