Establishment of a normal reference value for serum ß2 microglobulin in Japanese children: reevaluation of its clinical usefulness.

OBJECTIVE: Serum ß2 microglobulin (ß2MG) is considered to be a marker of renal function, which is independently associated with age. However, only a few studies have reported the reference values for ß2MG in children thus far, particularly in young children. In this study, we evaluated the distribution of serum ß2MG values in healthy Japanese children and assessed its clinical usefulness. METHOD: The normal reference value of serum ß2MG was assessed in serum samples from 1131 normal Japanese children (504 boys and 627 girls; age 0-17 years). To test the validity of the reference value, serum samples from children with various kidney diseases were also examined retrospectively. RESULTS: The mean values for ß2MG were significantly negatively correlated with age (r = -0.47, P < 0.001). No significant difference was observed between the values of boys and girls in any age group. The established ß2MG reference range covered 99.7 % of patients with decreased kidney function below 75 % based on their serum creatinine (Cr) value and body length. CONCLUSION: The newly established ß2MG reference value in children can be used to detect kidney impairment in children. Serum ß2MG in combination with serum Cr used as markers for predicting glomerular function can provide an accurate detection of kidney dysfunction in children.