What It Measures
A serum sodium test measures the concentration of sodium ions in the blood, reflecting the balance between sodium intake, kidney excretion, and water balance regulated by hormones like aldosterone and antidiuretic hormone (ADH/vasopressin).
Sodium is an essential electrolyte and the primary positively charged ion in extracellular fluid. It plays a critical role in maintaining fluid balance, blood pressure regulation, nerve impulse transmission, and muscle contraction. Abnormal sodium levels can indicate kidney dysfunction, hormonal imbalances, or hydration issues.
Current Value
What High Means
Elevated sodium (hypernatremia, >145 mEq/L) typically indicates dehydration or water deficit rather than sodium excess. Causes include inadequate water intake, excessive water loss (diabetes insipidus, diarrhea, excessive sweating), or rarely excess sodium intake. It can also result from Cushing syndrome, hyperaldosterism, or certain medications (lithium, demeclocycline). Chronic mild hypernatremia is associated with increased cardiovascular risk and accelerated biological aging.
Possible Symptoms
Intense thirst, dry mouth and mucous membranes, decreased urination, dark urine, restlessness, irritability, muscle twitching, confusion, lethargy, seizures (severe cases), coma (extreme cases).
What Low Means
Low sodium (hyponatremia, <136 mEq/L) is the most common electrolyte disorder and can result from excess water retention (SIADH, heart failure, cirrhosis), sodium loss (diuretics, adrenal insufficiency, vomiting/diarrhea), or excessive water intake (polydipsia, endurance exercise). Severe hyponatremia (<120 mEq/L) is a medical emergency that can cause cerebral edema, seizures, and death.
Possible Symptoms
Nausea and vomiting, headache, confusion, fatigue, muscle weakness and cramps, irritability, restlessness, seizures (severe), loss of consciousness (severe), cerebral edema (critical).
Risk Factors
Dehydration, chronic kidney disease, heart failure, liver cirrhosis, SIADH (syndrome of inappropriate antidiuretic hormone), diabetes insipidus, adrenal insufficiency (Addison disease), diuretic use, endurance athletics, excessive alcohol consumption, certain medications (SSRIs, thiazides, ACE inhibitors).
Actionable Advice
Supplements
- •Electrolyte supplements (with sodium)
- •Magnesium glycinate
- •Potassium citrate
- •Vitamin D3
- •Licorice root (for low sodium/adrenal support)
Diet & Lifestyle
- •Stay adequately hydrated but avoid overhydration — drink to thirst rather than forcing excessive water
- •Include adequate salt in diet (especially if active or sweating heavily)
- •Monitor sodium if taking diuretics, SSRIs, or other medications that affect levels
- •Replace electrolytes during prolonged exercise (>60 min) or heat exposure
- •Limit excessive alcohol intake which can contribute to hyponatremia
- •If sodium runs high, focus on adequate water intake and reducing processed food sodium
- •Get kidney function tested regularly if sodium is persistently abnormal
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Historical Trend
Resources & Studies
All Readings
| Date | Value | Change |
|---|---|---|
| 2025-08-25 | 136 mmol/L | -4.0 |
| 2025-06-27 | 140 mmol/L | — |