Low albumin lowers total magnesium even when the free (ionised) magnesium is normal. Magnesium is essential for nerve, muscle and heart rhythm; low levels often accompany low potassium and calcium.
How to use the Corrected Magnesium Calculator
- Serum magnesium
- Albumin
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter serum magnesium and albumin.
Inputs explained
| Field | What to enter |
|---|---|
| Serum magnesium | Units: mmol/L, mg/dL, mEq/L |
| Albumin | Units: g/dL, g/L |
Example values
How the main result changes when Serum magnesium changes and everything else stays at the example values above:
| Serum magnesium (mmol/L) | Corrected magnesium (mmol/L) |
|---|---|
| 0.35 | 0.4 |
| 0.525 | 0.58 |
| 0.7 | 0.75 |
| 0.875 | 0.93 |
| 1.05 | 1.1 |
| 1.4 | 1.45 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Corrected Mg (mmol/L) = measured Mg + 0.005 × (40 − albumin g/L)
mg/dL = mmol/L × 2.431 · mEq/L = mmol/L × 2
Worked example
Inputs — Serum magnesium: 0.7 mmol/L; Albumin: 3 g/dL.
Results — Corrected magnesium = 0.75 mmol/L.
Key terms
- Hypomagnesaemia
- Low blood magnesium.
Frequently asked questions
What is a normal magnesium?
About 0.7–1.05 mmol/L (1.7–2.6 mg/dL).
What causes low magnesium?
Diuretics, proton pump inhibitors, alcohol, diarrhoea and poor intake.
Is correction always needed?
It is a rough adjustment; ionised magnesium is rarely available.