Beta-2-microglobulin in mesangial IgA nephropathy.

This study measured plasma beta 2-microglobulin (beta 2-m) in patients with mesangial IgA nephritis. Plasma beta 2-m was measured in 51 patients with IgA mesangial nephritis and in 50 normal controls using a Phadebas beta 2-m RIA kit available from Pharmacia Diagnostics (Uppsala, Sweden). The mean plasma beta 2-m in IgA nephritic patients (1.92 +/- 0.67 mg/l) was significantly different from that of healthy controls (1.33 +/- 0.41 mg/l; p less than 0.001). The mean plasma beta 2-m in non-IgA nephritic patients (1.83 +/- 0.73 mg/l) was also significantly different (p less than 0.001). Patients with IgA nephritis with glomerular sclerosis (n = 33) had significantly higher levels of beta 2-m (2.02 +/- 0.70 mg/l) than IgA nephritic patients without glomerular sclerosis (n = 18, 1.72 +/- 0.65 mg/l; p less than 0.025). In the group with IgA nephritis and glomerulosclerosis, raised beta 2-m levels were correlated with the severity of proteinuria (r = 0.41) (p less than 0.02) as well as the intensity of IgA staining on immunofluorescence (r = 0.34; p less than 0.05). Elevated beta 2-m levels in IgA nephritis may serve as a useful prognostic marker.