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Electrolytes & Minerals

Magnesium (Mg²⁺)

Normal range 1.6–2.6 mg/dL (0.66–1.07 mmol/L SI). Specimen: Serum.

Also known as: serum magnesium.

1.6–2.6 mg/dLCritical: read below

Reference range

Conventionalmg/dL
1.62.6
SImmol/L
0.661.07
SpecimenSerum
Conventional range1.6–2.6 mg/dL
SI range0.66–1.07 mmol/L
Conversion factor×0.411 (conventional → SI)
Critical value< 1.0 or > 4.9 mg/dL
PanelElectrolytes & Minerals

Convert any Magnesium (Mg²⁺) result between units on the unit converter.

What is the normal range for Magnesium (Mg²⁺)?

The standard teaching reference range for Magnesium (Mg²⁺) is 1.6–2.6 mg/dL in conventional units, or 0.66–1.07 mmol/L in SI units. This value is measured in serum.

A commonly taught critical (panic) value is < 1.0 or > 4.9 mg/dL. Critical results are reported to the provider immediately under your facility's policy.

Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population — always use the range printed on the actual result.

Above the range

Common causes of a high Magnesium (Mg²⁺)

  • Renal failure
  • Excess magnesium (antacids, laxatives, treatment of pre-eclampsia)
  • Adrenal insufficiency

Below the range

Common causes of a low Magnesium (Mg²⁺)

  • Alcohol use disorder
  • Malnutrition or malabsorption
  • Diuretics
  • Refeeding syndrome

At the bedside

Nursing considerations

  • Low magnesium causes refractory hypokalemia and hypocalcemia — replace it too.
  • Monitor deep tendon reflexes; loss of reflexes signals magnesium toxicity.

Study aid

Your notes on Magnesium (Mg²⁺)

Same panel

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