Serum Magnesium Concentrations in the United States-An Updated Population Reference Interval in Children and Adults

Serum magnesium is a practical biomarker for assessing nutritional status in clinical settings, yet reference intervals commonly used in the United States largely reflect data from NHANES I (1971-1974).

The aim of this study is to describe serum magnesium concentrations across the US population and establish contemporary population-based reference intervals for children and adults.

This cross-sectional study used data from nonpregnant and nonlactating civilian participants in the 2021-2023 NHANES data cycles. Reference intervals were estimated following the International Federation of Clinical Chemistry recommendations. Primary analyses categorized children (aged 12-18 y) by sex and adults (aged ≥19 y) by sex, age, and metabolic health status [total population, metabolically healthy, hypertension, diabetes, and chronic kidney disease (CKD)]. Linear regression models were used to compare subgroups, and sensitivity analyses were conducted to assess robustness of primary findings.

The final analytic sample included 787 children and 5474 adults. Girls had significantly lower mean serum magnesium than boys (P = 0.003), although differences were small. The reference interval was 1.70-2.19 mg/dL (0.70-0.90 mmol/L; 1.40-1.80 mEq/L) for boys and 1.64-2.18 mg/dL (0.68-0.90 mmol/L; 1.35-1.79 mEq/L) for girls based on data from the total population. Mean serum magnesium concentrations were significantly lower in adult males and females with diabetes (P < 0.001; P < 0.001), hypertension (P = 0.012; P = 0.029), or CKD (P = 0.007; P = 0.002) compared with those who were metabolically healthy, respectively, and in females compared with males (P < 0.001). The reference interval was 1.72-2.26 mg/dL (0.71-0.93 mmol/L; 1.42-1.86 mEq/L) for males and 1.70-2.21 mg/dL (0.70-0.91 mmol/L; 1.40-1.82 mEq/L) for females based on data from the metabolically healthy population. Estimated prevalence of chronic latent magnesium deficiency (CLMD), represented by a serum magnesium concentration <2.06 mg/dL (0.85 mmol/L; 1.70 mEq/L), was 67.8% in adults.

This study provides contemporary population-based reference intervals for serum magnesium for children and adults and suggests that a substantial portion of the US population is at risk of CLMD.