What is a normal sodium-to-potassium ratio?

The normal serum Na/K ratio is generally 20–35. Some references quote 25–35 as a tighter normal band. Values outside this range warrant further clinical evaluation.

What does a low Na/K ratio indicate?

A low ratio (below 20) suggests either low sodium, high potassium, or both. Clinically, this pattern is associated with adrenal insufficiency (Addison's disease), where aldosterone deficiency causes sodium wasting and potassium retention.

What does a high Na/K ratio indicate?

A high ratio (above 35) may reflect hypernatremia (high sodium) or hypokalemia (low potassium). Causes include dehydration, excess aldosterone (primary hyperaldosteronism), diuretic use, or inadequate potassium intake.

Are the units mEq/L or mmol/L?

Both units are numerically equivalent for sodium and potassium (1 mEq/L = 1 mmol/L for monovalent ions), so you can use either without conversion. Use whatever your lab report shows.

Is this tool a substitute for clinical diagnosis?

No. This calculator is for educational and reference use only. All electrolyte results must be interpreted in the full clinical context by a qualified healthcare professional.

Sodium Potassium Ratio

Name: Sodium Potassium Ratio
Availability: InStock
Author: Nham Vu

Enter serum sodium and potassium values to calculate the Na/K ratio and get an instant clinical interpretation.

Serum Lab Values

Serum Sodium (Na⁺) mEq/L or mmol/L

Normal range: 135–145 mEq/L

Serum Potassium (K⁺) mEq/L or mmol/L

Normal range: 3.5–5.0 mEq/L

Reference Ranges

Na/K Ratio	Interpretation
< 20	Low — possible adrenal insufficiency
20–35	Normal
> 35	High — possible hypokalemia or hypernatremia

Enter values and click Calculate to see your result.

Summary