The clinical use of serum beta-2-microglobulin and fractional beta-2-microglobulin excretion in IgA nephropathy.

We measured serum beta-2-microglobulin (B2-m) and fractional beta-2-microglobulin excretion in 29 patients with IgA nephropathy. The mean serum B2-m in IgA nephropathy patients was significantly higher than that of healthy controls (p less than 0.025). The serum B2-m correlated well with serum creatinine and endogenous creatinine clearance (p less than 0.01). Patients with diffuse mesangial proliferation and glomerulosclerosis had a significantly higher level of B2-m than those with minor glomerular pathology (p less than 0.01). Patients with hypertension had significantly different levels of serum B2-m from normotensive patients (p less than 0.01). The mean fractional B2-m excretion in IgA nephropathy patients was significantly higher than that of healthy controls (p less than 0.001). Patients with moderate tubulo-interstitial involvement had significantly higher fractional B2-m excretion than those with mild tubulo-interstitial changes (p less than 0.01). Our study suggests that serum B2-m and fractional B2-m excretion may be useful indicators in the long-term prognosis of patients with IgA nephropathy.