Serum Sodium (Na)
Sodium is the principal extracellular cation, governing total body water distribution, intravascular volume, and transmembrane electrical potential across excitable tissues.
Standard vs. Optimal Reference RangesmEq/L
Standard reference intervals represent the statistical 95% distribution of unselected commercial populations. Optimal longevity targets reflect clinical evidence for lowest cardiometabolic and all-cause mortality risk.
Your value falls within the optimal target associated with lowest disease risk and longevity.
135 - 145 mEq/L
General reference distribution across unselected commercial populations.
138 - 142 mEq/L
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
Regulated by central hypothalamic osmoreceptors controlling arginine vasopressin (ADH) secretion and the juxtaglomerular renin-aldosterone cascade acting on renal epithelial sodium channels (ENaC).
Differential Diagnosis
Elevated Levels (Na High)
- •Hypovolemic hypernatremia (free water loss, sweating, diabetes insipidus)
- •Hypervolemic hypernatremia (excess sodium bicarbonate therapy)
Low Levels (Na Low)
- •SIADH (Syndrome of Inappropriate ADH)
- •Heart failure / Cirrhosis (hypervolemic hyponatremia)
- •Thiazide diuretic therapy
Technical Reference & Deep Dive
Biochemistry & Enzymatic Pathways
Longevity Risk Architecture & Epidemiology
Pre-Analytical Caveats & Diagnostic Workup
Pre-Analytical Considerations:
Maintain standard hydration status prior to venipuncture; acute hypovolemia or hemoconcentration artificially elevates concentrations. Avoid heavy resistance training and high-protein meals (especially cooked red meat) for 24 hours prior if testing serum creatinine. Ensure tourniquet time does not exceed 60 seconds to avoid pseudohyperkalemia or hemoconcentration of electrolyte fractions.
Reflexive Testing Protocol:
- Simultaneous Serum Cystatin C testing to calculate composite CKD-EPI Creatinine-Cystatin C eGFR equation
- Spot Urine Albumin-to-Creatinine Ratio (uACR) to detect subclinical glomerular endothelial leak
- Renal duplex ultrasonography to assess bilateral kidney dimensions, cortical echogenicity, and resistive index
- Fractional Excretion of Sodium (FENa) and Urea (FEUrea) to differentiate prerenal azotemia from intrinsic acute kidney injury
- Serum and urine protein electrophoresis (SPEP/UPEP) if tubular injury or monoclonal gammopathy is suspected
Clinical Citations & Primary Literature (1)
- [1]Middle-Age High Normal Serum Sodium as a Risk Factor for Accelerated Biological Aging - eBioMedicine (Lancet Discovery Science) (2023). PMID: 36599787
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate Serum Sodium (Na) into overall healthspan optimization.