How much sodium is in your urine directly reflects how much sodium you eat. According to the University of California San Francisco, normal urine sodium values for adults are generally 20 mEq/L in a random urine sample and 40 to 220 mEq per day. This base amount has been important because it’s been widely assumed that any observed correlation might indicate a causal connection between sodium ingestion and blood pressure (BP).
Urinary traits reflect the complex relationship between dietary intake, the general balance and function of kidneys and how they expel sodium and potassium, and other genetic mechanisms. However, biological mechanisms that link these traits are not exactly clear. To understand the genetic and physiological pathways underlying these electrolytes and their link to BP and cardiovascular events, researchers undertake a genome-wide association study (GWAS) on urinary sodium and potassium excretion among 446,237 European individuals in UK Biobank (UKB).
This study measured sodium and potassium concentrations in stored urine samples by the ion-selective electrode method. They identified 50 sodium and 13 potassium novel loci with statistical significance. Most of these loci had previously been found to be associated with lipid levels, anthropometric and lifestyle traits such as dietary intake, smoking-related behavior, and alcohol consumption at a significance level. Those genetic variants related to urinary sodium included rs2472297, rs838133 in the FGF21 gene, rs1260326 in the GCKR gene, rs4410790 in the LOC101927609 gene, rs2504671, rs816366 in the MLIP gene, rs4788415 in the DCTPP1, rs7072776 in the MLLT10, rs1229984 in the ADH1B gene and rs7334078 in the STK24 gene. In pathway analyses, sodium and potassium excretion loci are over-represented in biological functions involving behavioral response to stimuli, thermoregulation, and weight loss. A subset of loci involved in the behavioral response to stimuli supports a link to BP and coronary artery disease based on Mendelian randomization (MR) analysis. This study highlights a connection between urine sodium and potassium and cardiovascular traits. In addition, this study highlights a potential role for urinary sodium loci involved in thermoregulatory pathways in the regulation of BP.
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