From the Guidelines
Magnesium blood tests are crucial for diagnosing and managing magnesium-related disorders, with normal ranges typically between 1.7-2.2 mg/dL, and serum magnesium concentration between 1.3 to 2.2 mEq/L, as defined by the American Heart Association guidelines 1, 2. When interpreting magnesium labs, it's essential to consider the clinical context and potential causes of abnormal levels.
- Low magnesium (hypomagnesemia) can result from poor diet, certain medications like diuretics, alcoholism, or digestive disorders, and is defined as a serum magnesium concentration <1.3 mEq/L 1.
- High magnesium (hypermagnesemia) is less common but may occur with kidney dysfunction or excessive supplementation, and is defined as a serum magnesium concentration >2.2 mEq/L, with neurological symptoms including muscular weakness, paralysis, ataxia, drowsiness, and confusion 2. Treatment depends on the results—low levels may require dietary changes or supplements (typically 200-400 mg daily of magnesium oxide, citrate, or glycinate), while high levels might require addressing the underlying cause. Magnesium is essential for over 300 biochemical reactions in the body, including muscle and nerve function, blood glucose control, and bone health, making proper levels crucial for overall health. In certain situations, such as cardiac surgery, maintaining serum magnesium levels may be important to prevent postoperative arrhythmias, although the evidence for magnesium supplementation in this context is limited and inconclusive 3.
From the Research
Magnesium Labs
- Magnesium plays a crucial role in various physiological functions, and its deficiency can lead to chronic degenerative diseases 4.
- The assessment of magnesium status is essential, but its evaluation can be challenging; the measurement of serum magnesium concentration is the most commonly used method, despite its limitations 4, 5.
- Serum magnesium concentration has no reliable correlation with total body magnesium levels or concentrations in specific tissues, making it essential to consider other indicators, such as urinary magnesium excretion and dietary magnesium intake 5, 6.
Indicators of Magnesium Status
- Serum magnesium concentration: a reference range of 0.75 to 0.95 mmol/L is often used, but values below 0.85 mmol/L may be associated with increased health risks 7.
- Urinary magnesium excretion: a 24-h urine collection can be used to evaluate potential magnesium deficiency, and improvements in magnesium deficient state can be observed after dietary adjustments 8.
- Dietary magnesium intake: assessing magnesium intake is crucial, as low intake can lead to magnesium deficiency; the combined determination of serum magnesium concentration, urinary magnesium excretion, and dietary magnesium intake provides a sound assessment of magnesium status 6.
Clinical Implications
- Magnesium deficiency can have serious health consequences, including increased risk of type 2 diabetes, cardiovascular diseases, and chronic kidney disease 7, 6.
- Clinicians should consider assessing magnesium status in patients presenting with these disorders, using a combination of serum magnesium concentration, urinary magnesium excretion, and dietary magnesium intake 6.