Understand your RBC magnesium Blood Test Results…

This page helps you to understand blood test results for RBC magnesium and gives you the reference range to determine if your lab test results mean that you have high, low or normal RBC magnesium levels. 

We outline the risk factors associated with both raised and lower RBC magnesium levels.

Reference Ranges for RBC magnesium:

Measurement unit Metric Optimal Risk
US Conventional Units mg/dl 4.2-6.8 <4.2 or >6.8
Standard International Units mmol/L 1.7-2.8 <1.7 or >2.8
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What is RBC Magnesium

Magnesium, an abundant mineral in the body and is naturally present in many foods. Our ancient ancestors would have had a ready supply from organ meats, seafood, mineral water, and even swimming in the ocean, but modern soils can be depleted of minerals and magnesium is removed from water during routine treatment meaning that we are more likely to be deficient these days [104].

Assessing magnesium status with a blood test is difficult because most magnesium is inside cells or in bone. Measuring the amount of magnesium located within the red blood cells can give a more accurate result then serum magnesium levels, however to comprehensively evaluate magnesium status, both blood tests and a clinical assessment might be required [104].

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Function of RBC Magnesium

Magnesium is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation. Magnesium is required for energy production and it contributes to the structural development of bone and is required for the synthesis of DNA, RNA, and the antioxidant glutathione. Magnesium also plays a role in the active transport of calcium and potassium ions across cell membranes, a process that is important to nerve impulse conduction, muscle contraction, and normal heart rhythm [104].

Magnesium is sometimes called the relaxation mineral and is thought to have a calming effect on the central nervous system.

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Risk factors associated with RBC Magnesium

Because of the number of functions that magnesium is involved in, being deficient in this mineral can have a number of implications for your health:

Heart Disease – Studies have found that higher serum levels of magnesium were significantly associated with a lower risk of cardiovascular disease, and higher dietary magnesium intakes (up to approximately 250 mg/day) were associated with a significantly lower risk of ischemic heart disease which is caused by a reduced blood supply to the heart muscle [104].

Type 2 diabetes – Diets with higher amounts of magnesium are associated with a significantly lower risk of diabetes, possibly because of the important role of magnesium in glucose metabolism. Magnesium deficiency may worsen insulin resistance, a condition that often precedes diabetes, or it might be a consequence of insulin resistance.  Diabetes leads to increased urinary losses of magnesium, and the subsequent magnesium inadequacy may impair insulin secretion and action, thereby worsening diabetes control [104].


Osteoporosis – Magnesium is involved in bone formation and influences the activities of osteoblasts and osteoclasts. Several population-based studies have found positive associations between magnesium intake and bone mineral density in both men and women. Other research has found that women with osteoporosis have lower serum magnesium levels [104].

Migraine headaches – People who experience migraine headaches have lower levels of serum and tissue magnesium than those who do not. However, research on the use of magnesium supplements to prevent or reduce symptoms of migraine headaches is limited. Three of four small, short-term, placebo-controlled trials found modest reductions in the frequency of migraines in patients given up to 600 mg/day magnesium [104].

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Notable variations by demographic group

People with gastrointestinal diseases – Diarrhea and fat malabsorption resulting from Crohn’s disease, gluten-sensitive enteropathy (celiac disease), and regional enteritis can lead to magnesium depletion over time. Resection or bypass of the small intestine, especially the ileum, typically leads to malabsorption and magnesium loss [104].

People with type 2 diabetes – Magnesium deficits and increased urinary magnesium excretion can occur in people with insulin resistance and/or type 2 diabetes. The magnesium loss appears to be secondary to higher concentrations of glucose in the kidney that increase urine output [104].

People with alcohol dependence – Magnesium deficiency is common in people with chronic alcoholism [2]. In these individuals, poor dietary intake and gastrointestinal problems can contribute to decreased magnesium status [104].

Older adults – Older adults have lower dietary intakes of magnesium than younger adults. In addition, magnesium absorption from the gut decreases and renal magnesium excretion increases with age [104].

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Diet to improve RBC Magnesium

Magnesium is widely distributed in plant and animal foods. Green leafy vegetables, such as spinach, legumes, nuts, seeds, and whole grains, are good sources. In general, foods containing dietary fibre provide magnesium. Some types of food processing, such as refining grains in ways that remove the nutrient-rich germ and bran, lowering magnesium content substantially [104].

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Supplements for RBC Magnesium

Magnesium supplements are available in a variety of forms, including magnesium oxide, citrate, and chloride. Absorption of magnesium from different kinds of magnesium supplements varies. Studies have found that magnesium in the citrate and chloride forms is absorbed more completely and is significantly more bioavailable than magnesium oxide and magnesium sulphate [104].

Epsom salt bats and transdermal magnesium oils are also effective ways to boost levels of magnesium in the body, particularly for people who have digestive issues.

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Exercise to improve RBC Magnesium

Magnesium is involved in numerous processes that affect muscle function including oxygen uptake, energy production and electrolyte balance. Thus, the relationship between magnesium status and exercise has received significant research attention. There is evidence that magnesium deficiency impairs exercise performance and amplifies the negative consequences of strenuous exercise, so a magnesium deficiency should be corrected before participating in intense exercise.

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Sleep for RBC Magnesium

In magnesium deficiency, chronic insomnia is one of the main, central symptoms. Sleep is usually agitated with frequent night-time awakenings. On the other hand, a high magnesium, low aluminium diet has been found to be associated with deeper, less interrupted sleep [105].