Korean J Intern Med.  2014 May;29(3):334-340. 10.3904/kjim.2014.29.3.334.

Urinary excretion of beta2-microglobulin as a prognostic marker in immunoglobulin A nephropathy

• Shin JR
• Kim SM
• Yoo JS
• Park JY
• Kim SK
• Cho JH
• Jeong KH
• Lee TW
• Ihm CG

• KMID: 1792059
• DOI: http://doi.org/10.3904/kjim.2014.29.3.334

Abstract

BACKGROUND/AIMS
beta2-microglobulin (beta2-MG) is freely filtered at the glomerulus and subsequently reabsorbed and catabolized by proximal renal tubular cells. Urinary beta2-MG is an early and sensitive biomarker of acute kidney injury; however, its utility as a biomarker of immunoglobulin A nephropathy (IgAN) is unclear.
METHODS
We included urinary beta2-MG levels in the routine laboratory examination of all inpatients with biopsy-proven IgAN at our hospital from 2006 to 2010. We retrospectively analyzed the correlation between beta2-MG levels and clinical parameters as a prognostic biomarker of IgAN.
RESULTS
A total of 51 patients (30 males, 21 females; mean age, 33.01 +/- 12.73 years) with IgAN were included in this study. Initial demographic, clinical, and laboratory data for all patients are listed. The mean initial estimated glomerular filtration rate and 24-hour urine protein levels were 94.69 +/- 34.78 mL/min/1.73 m2 and 1.28 +/- 1.75 g/day, respectively. The mean level of urinary beta2-MG was 1.92 +/- 7.38 microg/mg creatinine. There was a significant correlation between initial serum creatinine (iSCr), urine protein creatinine ratio (UPCR), and the level of beta2-MG (r = 0.744, r = 0.667, p < 0.01). There was also a significant correlation between renal function tests and the level of urinary beta2-MG (p < 0.01). Cox regression analysis showed that albumin, beta2-MG, iSCr, and UPCR were significant predictors of disease progression in IgAN.
CONCLUSIONS
Urinary beta2-MG levels showed a significant correlation with renal function and proteinuria in IgAN. Thus, we propose that urinary beta2-MG may be an additional prognostic factor in patients with IgAN.

Keyword

Urinary beta2-microglobulin; Glomerulonephritis, IGA; Prognostic factor

MeSH Terms

Adult
Biological Markers/blood/urine
Biopsy
Creatinine/blood/urine
Disease Progression
Female
Glomerular Filtration Rate
Glomerulonephritis, IGA/blood/diagnosis/physiopathology/*urine
Humans
Inpatients
Linear Models
Male
Middle Aged
Multivariate Analysis
Predictive Value of Tests
Prognosis
Proportional Hazards Models
Proteinuria/blood/diagnosis/physiopathology/*urine
Risk Factors
Young Adult
beta 2-Microglobulin/*urine
Biological Markers
Creatinine
beta 2-Microglobulin