---
title: "What does a high Sodium mean?"
type: biomarker-interpretation
url: "https://www.test-well.com/biomarkers/sodium/high"
biomarker: Sodium
direction: high
reference_range:
  - "age 18+: 135 – 145 mmol/L"
reviewed_at: 2026-09-06
review_status: reviewed
date_published: 2026-09-05
---

# What does a high Sodium mean?

> High sodium (hypernatremia) almost always means water loss exceeding intake — not eating too much salt. Dehydration from illness, heavy sweating, diuretics, uncontrolled diabetes, or an impaired sense of thirst (older adults, certain brain conditions) are typical causes; diabetes insipidus is rare. Mild elevations correct with fluids; significant ones need medical evaluation.


## When does this result need same-day care?

- Sodium above about 150 mmol/L, or any elevation with confusion — same-day care

## What is the normal range for Sodium?

- age 18+: 135 – 145 mmol/L

Often reflects dehydration or excess salt intake.

## What are the common causes of high Sodium?

1. Dehydration: inadequate water intake, fever, heat, vomiting, diarrhea
2. Osmotic diuresis from very high glucose
3. Diuretics, lithium (impairs water retention)
4. Impaired thirst in older adults or neurological disease
5. Diabetes insipidus (rare)

## What symptoms go with high Sodium?

- Thirst, dry mouth
- Confusion, lethargy, irritability when marked

## What do clinicians usually check next?

- Repeat after rehydrating
- Glucose, kidney function
- Urine osmolality if persistent

Follow-up tests at TestWell: [Glucose](https://www.test-well.com/tests/glucose-basic) ($14.99).

## How do you recheck Sodium?

| Test or panel | Type | Price | Fasting | Results |
| --- | --- | --- | --- | --- |
| [Basic Metabolic Panel](https://www.test-well.com/tests/basic-metabolic-panel) | Test | $20.99 | Yes | 1–3 business days |

Plus one $6 lab processing fee per order; physician authorization included.

## Common questions

### Does a salty diet raise blood sodium?

Not in a healthy person — the kidneys and thirst keep it tightly regulated. High sodium on a lab test is a water problem, not a salt problem.

## Related

- [What does a low Sodium mean?](https://www.test-well.com/biomarkers/sodium/low)
- [Sodium reference ranges](https://www.test-well.com/biomarkers/sodium)
- [Glucose reference range](https://www.test-well.com/biomarkers/glucose)
- [Creatinine reference range](https://www.test-well.com/biomarkers/creatinine)
- [eGFR reference range](https://www.test-well.com/biomarkers/egfr)

## Sources

- [Mayo Clinic Labs](https://www.mayocliniclabs.com/test-catalog/overview/8533)

---

Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-09-06. Review policy: https://www.test-well.com/editorial-policy

Canonical page: https://www.test-well.com/biomarkers/sodium/high
Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt

Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.