---
title: "What Is Hyponatremia? Heat Stress and Hydration Glossary"
description: "Hyponatremia is low blood sodium: a sodium level lower than normal. It can follow long sweating when a person drinks lots of plain water without replacing salts."
url: https://jmarsolutions.multisites.ai/glossary/hyponatremia
publisher: JMAR Solutions
phone: +1-214-632-7780
quote: https://jmarsolutions.multisites.ai/contact
---

Hydration science

# Hyponatremia

Hyponatremia is low blood sodium: a sodium level lower than normal. It can follow long sweating when a person drinks lots of plain water without replacing salts.

Hyponatremia is the medical name for low blood sodium. MedlinePlus defines it as a condition in which the sodium level in the blood is lower than normal. Heavy sweating is one listed cause on that page.

On a jobsite, the risk grows when a worker sweats for hours and drinks large amounts of plain water. Water alone does not replace [sodium](https://jmarsolutions.multisites.ai/glossary/sodium). NIOSH says fluid intake should generally not exceed 6 cups per hour. Read our [hyponatremia at work guide](https://jmarsolutions.multisites.ai/guides/hyponatremia-at-work) and the [electrolytes 101 guide](https://jmarsolutions.multisites.ai/guides/electrolytes-101). Balanced [electrolytes](https://jmarsolutions.multisites.ai/glossary/electrolyte) matter on long shifts.

[From JMAR SolutionsHydration programs and toolbox talks for crews](https://jmarsolutions.multisites.ai/hydration-programs)

## Related terms

-   [Sodium](https://jmarsolutions.multisites.ai/glossary/sodium)
-   [Electrolyte](https://jmarsolutions.multisites.ai/glossary/electrolyte)
-   [Hydration](https://jmarsolutions.multisites.ai/glossary/hydration)
-   [Sweat rate](https://jmarsolutions.multisites.ai/glossary/sweat-rate)

## Sources

1.  [MedlinePlus: Low blood sodium](https://medlineplus.gov/ency/article/000394.htm)
2.  [CDC NIOSH: Heat Stress Workplace Recommendations](https://www.cdc.gov/niosh/heat-stress/recommendations/index.html)

![Ironworkers silhouetted on a steel frame against a hot orange sunset](https://jmarsolutions.multisites.ai/_astro/sunset-steel.IhAMDca0_6wk53.webp)

## See it on your crew in 15 minutes

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