• What can contribute to low magnesium stores?

The Arabic service information lists low dietary intake, intestinal malabsorption, excessive renal or gastrointestinal losses, and increased requirements such as pregnancy, lactation, or intensive exercise.

Medical Laboratories

RBC Magnesium Storage Test

Red Blood Cell (RBC) Magnesium Test

Measure magnesium levels within red blood cells for a more accurate assessment of total body stores, detecting hidden deficiencies that standard serum tests might miss.

Trusted medical contentUpdated: 04-09-2026Views: 105LHL-1057

About this service

The red blood cell magnesium (RBC) test measures the level of magnesium within red blood cells. Unlike serum magnesium, which measures only the free, extracellular portion, this test is a more accurate indicator of total cellular magnesium levels in the body, since 99% of magnesium is found within cells. It is useful for assessing long-term magnesium status.

Conditions and notices

Fasting is not required

Fasting is not mandatory for this test, but fasting for 8-12 hours may give more consistent results.

The sample is collected in a special tube containing an anticoagulant (heparin or EDTA), and the red blood cells must be quickly separated from the serum after the blood is drawn to prevent magnesium from leaking out.

The doctor should be informed of all medications and dietary supplements the patient is taking, especially diuretics and magnesium or calcium supplements.

Frequently Asked Questions

Short answers to the FAQs published with this service.

• Why might athletes need to check their RBC magnesium levels?

Athletes are at risk of losing significant amounts of magnesium through sweat and often have higher metabolic demands.

• Does the RBC magnesium test require fasting?

No, fasting is not required for this laboratory blood test.

• What is the primary goal of measuring magnesium inside red blood cells?

The goal is to evaluate actual intracellular magnesium status and identify hidden (latent) magnesium deficiency that might not be visible in a standard serum magnesium test.

• How does RBC magnesium differ from a standard serum magnesium test?

RBC Magnesium Storage Test

About this service

What is included?

Conditions and notices

Frequently Asked Questions

Choose a provider and branch

Let us help you

Didn’t find the service?

Services you might also like

Keep Your Body Mercury-Free

Serum Iron (Fe) Test

Insulin Level Test

Balance Your Minerals and Bone Health

Your opinion matters

Was this content helpful?

Have a note?