Urinary Beta 2 microglobulin in various grades of renal scar in pyelonephritis in children

Background: For patients who have renal involvement during urinary infection or children with Vesico-ureteral Reflux (VUR), renal Dimercaptosuccinic Acid (DMSA) scan is performed which exposes children to significant radiation. β₂MG is a low molecular weight protein freely filtered by the glomeruli and then actively reabsorbed normally up to 99.9% in the proximal tubules; its urinary measurement is a good index of proximal tubular function of these cells as a primary screening test.
Methods: Urinary β₂MG/Cr was measured in random urine samples in 53 pyelonephritis patients. Urine samples were obtained at the time of Voiding Cysto-Ureterography (VCUG). DMSA renal scan was performed in all patients. β₂MG and urine creatinine were tested by ELISA and autoanalyzer, respectively.
Findings: Twenty children had various grades of renal scar. Results were compared with ratios of 19 children with low uptake scanning and with 14 normal scanning. The mean urinary β₂MG/Cr was higher in the scarring group (5.23±10.6) than in the normal group (0.19±0.2) and in low uptake group (0.49±0.86). Patients with grade 3 had higher values (14.69± 15.82) than grades 1 (0.36± 0.35) and 2 (3.37± 5.2). Patients without renal scar had β₂MG/Cr ratio below 0.46 microgram/mg. The mean β₂MGMG was higher in the VUR group (3/45± 7.97) than non-VUR group (0.23 ± 0.24) ug/mgCr (P= 0.01). The mean β₂MG/Cr was higher in patients with VUR grades 4 and 5 (8.93±12.01) than patients with VUR grades 1 to 3 (0.81± 3.04) (P= 0.02).
Conclusion: This study revealed that the maximum B₂MG/Cr value in non-VUR children was 0.85 microgram/mgCr, higher values can be considered as a cut off point in screening children for VUR. Measurement of Urinary B₂MG may be useful in the early detection of tubular damage in VUR patients and patients with renal scars.

Keywords
Beta 2 microglobulin , Renal scar , Pyelonephritis Children , Vesico-ureteral reflux