Serum magnesium: time for a standardized and evidence-based reference range.

Magnesium deficiency can have serious health consequences. Low magnesium intake or low serum levels are risk factors for e.g. type 2 diabetes and cardiovascular diseases. Despite its scientifically recognized importance, too little attention is paid to magnesium in clinical practice. This may be due to the fact that there is no uniform and evidence-based reference range for serum magnesium as is the case for other electrolytes such as sodium and potassium. The serum magnesium concentration is also of a limited informative value, as it is maintained for a long time by releasing magnesium from body pools. A low serum magnesium is a definite sign of magnesium deficiency; however, values within the reference range do not rule out deficiencies. Nevertheless, serum magnesium should become part of routine diagnostics in order to be able to better detect deficiency states. For serum magnesium, a reference range of 0.75 to 0.95 mmol/L (1.82 to 2.31 mg/dL) can often be found. However, according to the current data situation, serum magnesium values of less than 0.85 mmol/L are associated with increased health risks. Therefore, the lower limit of the reference range should be raised to 0.85 mmol/L (2.07 mg/dL).