Potassium · low result
What does a low Potassium mean?
Short answer
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.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
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.
Full reference table, citations and testing options: Potassium biomarker page.
What are the common causes of low Potassium?
- Diuretics (thiazides, loop diuretics)
- Vomiting, diarrhea, laxative use
- Low intake, alcohol use disorder, eating disorders
- Magnesium deficiency (potassium won't correct until magnesium does)
- Hyperaldosteronism, Cushing's syndrome, renal tubular disorders
- 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 available at TestWell: Magnesium ($19.99), Aldosterone ($61.99).
How do you recheck Potassium?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| Basic Metabolic Panel | Test · 8 biomarkers | $20.99 | Yes | 1–3 business days |
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.
Sources
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.