|See Also||Lab Tests|
The RBC magnesium test is used to evaluate the level of magnesium in the blood. This in turn can help to determine the cause of abnormal calcium and/or potassium levels. The test is usually conducted when a patient presents with symptoms such as weakness, irritability, cardiac arrhythmia, nausea, and/or diarrhea that may be due to too much or too little magnesium., 
- Magnesium is a mineral that is vital for energy production, muscle contraction, nerve function, and the maintenance of strong bones.
- It is obtained through diet, absorbed by the small intestine and colon, and stored in the bones, cells, and tissues.
- Normally, only 1% of total body magnesium is present in the blood.
- Overnight fasting may be required.
- Factors which can cause increased levels:
- Drugs: lithium, aspirin, thyroid medication, some antibiotics, and products that contain magnesium
- Factors which can cause decreased levels:
- pregnancy (particularly during the second and third trimesters)
- Drugs: digoxin, cyclosporin, diuretics, insulin, some antibiotics, laxatives, and phenytoin
High levels indicate:
- Kidney failure
- Diabetic acidosis (when first detected)
- Addison's disease
- Use of magnesium-containing antacids or laxatives
Low levels indicate:
- Malnutrition or low dietary intake
- Prolonged diarrhea
- Gastrointestinal disorders
- Uncontrolled diabetes
- Long-term diuretic use
- Post surgery
- Severe burns
- Toxemia or pregnancy
- Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.
- Weatherby Dicken, Ferguson Scott (2002) Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain.