Sodium
A key electrolyte that controls fluid balance and nerve and muscle function. Tightly regulated by the body.
Typical reference range
| Range | Unit |
|---|---|
| 137–145 | mmol/l |
What Sodium measures
Serum sodium measures the main electrolyte in your blood and is a key driver of fluid balance. A common misconception is that this result reflects how much salt you eat. In reality, blood sodium mostly reflects the balance between sodium and water in the body rather than dietary intake. The level is kept within a narrow band by the kidneys, the sense of thirst, and hormones such as antidiuretic hormone (ADH), which together adjust how much water is retained or passed. Because water and sodium move together, a change in this marker can point to a shift in hydration as much as in salt. Sodium is rarely read alone: a clinician usually interprets it alongside potassium and kidney markers on a metabolic panel.
What a high Sodium can mean
A high sodium level (hypernatremia) usually reflects too little water relative to sodium rather than eating too much salt. Because it is fundamentally a water-balance problem, the most common cause is dehydration from not drinking enough or from fluid losses. This is more commonly associated with older adults or with situations where thirst is blunted or access to water is limited, such as illness. Less commonly, it can be linked with hormonal causes that affect how the body holds onto water.
When a level is markedly raised, it may be associated with symptoms such as:
- strong thirst
- tiredness or weakness
- confusion or restlessness
Mild changes often cause no symptoms and may be found on routine testing. This result describes a pattern of water balance, not a diagnosis, and should be interpreted by a clinician alongside your kidney markers and overall picture.
What a low Sodium can mean
A low sodium level (hyponatremia) is one of the most common electrolyte abnormalities and usually reflects relatively too much water rather than too little salt. Because many different processes can shift water balance, it has a wide range of possible causes. These commonly include heart, liver, or kidney conditions, certain medications, hormonal causes such as the syndrome of inappropriate ADH (SIADH), and overhydration from drinking large amounts of fluid.
When a level is markedly low, it may be associated with symptoms such as:
- nausea
- headache
- confusion or feeling unsteady
Because a low result can arise from so many different situations, it needs a proper clinical work-up to understand the cause. This marker describes a pattern, not a diagnosis, and should be discussed with a clinician who interprets it alongside your other results and symptoms.
Track your Sodium over time in Quanome — it reads your lab reports (PDF or photo) on your device, charts each marker against its range, and an AI coach explains what your trends mean alongside your Apple Health and DNA.