Lab test

Magnesium RBC Test - Deficiency Testing

The magnesium RBC test measures the amount of magnesium inside red blood cells.

Typical price

From $158

Results

1-3 business days

Preparation

See preparation notes below

Sample

Blood draw or sample collection at a local center

The magnesium RBC test measures the amount of magnesium inside red blood cells. It is similar to the serum and urine magnesium tests, but some consider it a more accurate reflection of body magnesium status because it looks directly at how much magnesium the red blood cells contain. Magnesium is involved in muscle and nerve function, energy production, and bone health. This test may be ordered when a provider suspects a magnesium deficiency despite a normal serum level, or when symptoms persist after routine testing.

• Magnesium (red blood cell) Measures the magnesium content inside red blood cells.
• Magnesium (serum) Often measured alongside the RBC test for comparison.

• People with magnesium deficiency symptoms and a normal serum level
• Individuals with muscle cramps, twitching, or weakness
• People with conditions or medicines that affect magnesium balance
• Those being evaluated for persistent magnesium deficiency

• No fasting is usually required.
• Tell the collector about magnesium supplements or medicines you take.
• Follow any instructions provided for your specific panel.

A low red blood cell magnesium may suggest that body stores are low even when a serum level looks normal. A normal result does not always rule out deficiency, and results are interpreted with your symptoms, diet, and other magnesium tests. Discuss results with a healthcare provider, who can determine whether further evaluation is needed.

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