Serum beta-2-microglobulin estimation as an indicator of the glomerular filtration rate

In 56 patients in whom the glomerular filtration rate (GFR) was estimated by the ⁵¹Cr-EDTA technique, serum creatinine and B₂-microglobulin levels were also measured. In the 15 patients with a GFR of ≥ 80 ml/min, both serum creatinine and B₂-microglobulin levels were within the relerence range. However, the B₂-microglobulin level was elevated (>2,3 mg/l) in all 41 patients with a GFR of < 80 ml/min, while the serum creatinine levels was increased (> 133 μmol/l) in only 35 patients. In the remaining 6 patients, the creatinine values ranged from 75 to 125 μmol/l. It would therefore seem that serum B₂-microglobulin assay is a more sensitive test than creatinine assay for detecting impaired renal function.