The Magnesium, RBC test measures the level of magnesium in your red blood cells, providing a more accurate picture of your magnesium status compared to serum magnesium levels. Magnesium is vital for various bodily functions, including muscle and nerve function, blood pressure regulation, and bone health. This test is important for individuals experiencing symptoms related to magnesium deficiency, such as muscle cramps or fatigue. Understanding your magnesium levels can help inform dietary choices and supplementation to support overall health.