---
title: "What does a low Potassium mean?"
type: biomarker-interpretation
url: "https://www.test-well.com/biomarkers/potassium/low"
biomarker: Potassium
direction: low
reference_range:
  - "age 18+: 3.50 – 5.00 mmol/L"
reviewed_at: 2026-09-06
review_status: reviewed
date_published: 2026-09-05
---

# What does a low Potassium mean?

> Low potassium (hypokalemia) most often follows losses — diuretics, vomiting, diarrhea, laxatives, heavy sweating — or low intake with alcohol use. Less common causes include high aldosterone, Cushing's syndrome, magnesium deficiency and some medications (insulin, beta-agonists, high-dose steroids). It causes cramps, weakness and, when severe, heart rhythm problems.


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

- Potassium below 2.5–3.0 mmol/L, or any low value with palpitations or severe weakness — same-day care

## What is the normal range for Potassium?

- age 18+: 3.50 – 5.00 mmol/L

Can reflect diuretic use, GI losses, or low intake.

## What are the common causes of low Potassium?

1. Diuretics (thiazides, loop diuretics)
2. Vomiting, diarrhea, laxative use
3. Low intake, alcohol use disorder, eating disorders
4. Magnesium deficiency (potassium won't correct until magnesium does)
5. Hyperaldosteronism, Cushing's syndrome, renal tubular disorders
6. Insulin, beta-agonist inhalers, high-dose glucocorticoids

## What symptoms go with low Potassium?

- Muscle cramps and weakness
- Fatigue, constipation
- Palpitations
- Paralysis or dangerous arrhythmias when very low

## What do clinicians usually check next?

- Magnesium (deficiency blocks correction)
- Blood pressure and aldosterone/renin if high blood pressure accompanies low potassium
- Review diuretics, laxatives and vomiting
- ECG if below about 3.0 mmol/L or symptomatic

Follow-up tests at TestWell: [Magnesium](https://www.test-well.com/tests/magnesium) ($19.99), [Aldosterone](https://www.test-well.com/tests/aldosterone-test) ($61.99).

## How do you recheck Potassium?

| 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

### Can I fix low potassium with bananas?

Diet helps mild cases, but the cause matters more — and low magnesium must be corrected first or potassium won't hold. Values below 3.0 need a clinician.

## Related

- [What does a high Potassium mean?](https://www.test-well.com/biomarkers/potassium/high)
- [Potassium reference ranges](https://www.test-well.com/biomarkers/potassium)
- [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/8528)

---

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/potassium/low
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.