[Beta 2 microglobulin. Index of glomerular filtration in children].

121 assays for plasma Beta 2 microglobulin (B2M) levels were carried out with an immuno-enzymatic technique in 94 children whose ages ranged from 13 months to 18 years and whose renal functions showed various levels of renal impairment. In the 37 children with normal glomerular filtration rate, plasma B2M level was 1.58 +/- 0.48 mg/l (mean +/- 1 SD) and no significant differences were found according to sex, ages or heights. In the 29 children with glomerular filtration rate (GFR) ranging from 20 to 100 ml/min/1.73 m2, there was a significant correlation between B2M and the inulin clearance, plasma creatinine level and creatinine clearance (p less than 0.001). In 28 patients presenting with terminal renal failure, plasma B2M levels were significantly higher in children undergoing hemodialysis than in those under chronic peritoneal dialysis. These results indicate that B2M levels are as good an index of glomerular filtration rate as serum creatinine whereas its assay uses a long and difficult technique.