Beta-2-microglobulin is superior to N-acetyl-beta-glucosaminidase in predicting prognosis in idiopathic membranous nephropathy.

Abstract

BACKGROUND:

An accurate prediction of prognosis in patients with idiopathic membranous nephropathy (iMN) would allow restriction of immunosuppressive treatment to patients who are at highest risk for end-stage renal disease (ESRD). Several markers of proximal tubular cell injury have been used as predictors of prognosis. In this study we compared the accuracy of urinary beta-2-microglobulin (U beta 2m) and N-acetyl-beta-glucosaminidase (U beta-NAG) in predicting renal insufficiency and remission rates.

METHODS:

Fifty-seven patients with iMN (38 M, 19 F; age 48 +/- 16 years), a nephrotic syndrome and a serum creatinine level <135 micromol/l were studied prospectively. At baseline, a standardised measurement was carried out to determine renal function and protein excretion. The end-point renal failure was defined as a serum creatinine exceeding 135 micromol/l or an increase in serum creatinine by >50%. Remission was defined as a proteinuria <2.0 g/day with stable renal function.

RESULTS:

The mean follow-up was 80 +/- 36 months. The mean serum creatinine concentration was 89 +/- 20 micromol/l, serum albumin 24 +/- 5.3 g/l and proteinuria 8.9 +/- 4.8 g/24 h. Thus far, 28 (49%) patients have reached the predefined end point of renal failure. Multivariate analysis identified U beta 2m as the strongest independent predictor for the development of renal insufficiency. Sensitivity and specificity were 81 and 90% respectively for U beta 2m (threshold value 54 microg/mmol cr), and 74 and 81% respectively for U beta-NAG (threshold value 2.64 U/mmol cr). The overall remission rate was 44%. A remission occurred in 78% of patients with low U beta 2m and in 14% of patients with high U beta 2m, and respectively in 71% of patients with low U beta-NAG and 21% of patients with high U beta-NAG.

CONCLUSIONS:

Although both U beta 2m and U beta-NAG predicted progression and remission in iMN, U beta 2m was more accurate. High specificity in predicting prognosis should be pursued to avoid unnecessary immunosuppressive therapy. We therefore conclude that U beta 2m is superior to U beta-NAG in predicting prognosis in patients with iMN.

• Authors: Julia M Hofstra, Jeroen K J Deegens, Hans L Willems, Jack F M Wetzels
• Journal: Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association (Nephrol Dial Transplant) Vol. 23 Issue 8 Pg. 2546-51 (Aug 2008) ISSN: 1460-2385 [Electronic] England
• PMID: 18308774 (Publication Type: Journal Article)

Chemical References

• Biomarkers
• Immunosuppressive Agents
• beta 2-Microglobulin
• Acetylglucosaminidase

Topics

• Acetylglucosaminidase (urine)
• Adult
• Biomarkers (urine)
• Female
• Glomerulonephritis, Membranous (complications, drug therapy, enzymology, urine)
• Humans
• Immunosuppressive Agents (therapeutic use)
• Kidney Failure, Chronic (enzymology, etiology, urine)
• Male
• Middle Aged
• Multivariate Analysis
• Nephrotic Syndrome (enzymology, urine)
• Prognosis
• Proportional Hazards Models
• Prospective Studies
• beta 2-Microglobulin (urine)