Serum magnesium is a practical biomarker for assessing nutritional status in clinical settings, yet reference intervals commonly used in the U.S. largely reflect data from NHANES I (1971–1974). To describe serum magnesium levels across the U.S. 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 International Federation of Clinical Chemistry (IFCC) recommendations. Primary analyses categorized children (12–18 y) by sex and adults (≥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 5,474 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 levels were significantly lower in adult men and women with diabetes (p<0.001; p<0.001), hypertension (p=0.012; p=0.029), or CKD (p=0.007; p=0.002) versus those who were metabolically healthy, respectively, and in women versus men (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 men and 1.70–2.21 mg/dL (0.70–0.91 mmol/L; 1.40–1.82 mEq/L) for women based on data from the metabolically healthy population. Estimated prevalence of chronic latent magnesium deficiency (CLMD), represented by a serum magnesium level <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 suggest that a substantial portion of the U.S. population is at-risk for CLMD.
Jiao et al. (Wed,) studied this question.