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Magnesium RBC

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About Our Magnesium RBC

Note: Fasting is not required for this test.

This blood test evaluates the level of magnesium in red blood cells for deficiency or toxicity.

Magnesium is a mineral that plays an important role in many biochemical reactions including your heartbeat, nerve and muscle function, bone development, energy production, glucose and blood pressure regulation and protein synthesis.

The Magnesium Test is often used to monitor individuals with kidney disorders or disease, or to evaluate individuals with symptoms of malnutrition or malabsorption.

The RBC magnesium test is very similar to the serum test, but it measures the amount of magnesium in red blood cells rather than the magnesium in the blood serum. The RBC test is viewed as more accurate than the serum test because when you are deficient in magnesium, your body takes it from cells instead, therefore, making it highly detectable through an RBC. The RBC may indicate that these red blood cells are missing a healthy level of magnesium, meaning you may have a magnesium deficiency. 


Deficient magnesium levels can lead to:

  • Muscle cramps/spasms/tremors
  • Fatigue/Somnolence
  • Decreased reflexes
  • Heart block
  • Inexplicably low calcium levels
  • Nausea
  • Loss of appetite
  • Seizures
  • Heart arrhythmia
  • Diarrhea

Magnesium levels that are high can be a sign of:

  • Renal (kidney) failure
  • Ingesting large amount of antacids
  • Addison disease
  • Pregnant patients with pre-eclampsia or eclampsia on anticonvulsant drugs

Magnesium deficiency can be more prevalent in people who:

  • Drink caffeinated drinks or alcohol often
  • Have malabsorption of vitamin D, which aids in magnesium absorption
  • Are uncontrolled diabetics
  • Eat a lot of refined sugar, which causes the body to excrete magnesium through the kidneys
  • Have Bartter syndrome or Gitelman syndrome
  • Are on corticosteroids

Major dietary magnesium sources include:

  • Leafy green vegetables like spinach
  • Squash
  • Pumpkin seeds
  • Nuts and seeds
  • Legumes
  • Fish
  • Whole grains

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