STUDIES ON REFLUX NEPHROPATHY, I
Evaluation of Renal Function by Urinary Excretion of β2-Microglobulin
1984 Volume 75 Issue 2 Pages 245-254
Details
1984 Volume 75 Issue 2 Pages 245-254
Urinary Excretion rate of β2-microglobulin (β2-MG) was determined to evaluate renal function of 74 children with sterile reflux. Spot urine was used for assay of urinary β2-MG and the ratio of urinary β2-MG to creatinine was calculated to correct the possible difference resulting from variable conditions of diuresis.
41% of the children with reflux showed abnormally high urinary ratio and high values were frequently observed in children with high grade reflux. However, over one-third of children with low grade reflux showed also high value, and there was no correlation between the grade of reflux and the urinary ratio. Although the urinary ratio exceeded the upper limit of normal range in 33% of cases with normal IVP and in 53% of those with abnormal IVP, there was no correlation between IVP finding and urinary ratio. Renal ratio (renal size), an index of renal growth, was also investigated and compared with urinary ratio.
The urinary ratio was high in 32% of children with normal sized kidneys and 74% of those with small sized kidneys. In a few cases with small sized kidney, however, it was within the normal range. This discrepancy may be due to reduced excretion of β2-MG from completely damaged nephrons associated with regional interstitial fibrosis.
The urinary ratio obtained before and after the antireflux operation demonstrated postoperative amelioration in all 11 cases with high preoperative values.
These results indicate that the renal disturbance was caused by sterile reflux alone and improved by elimination of reflux. It has also become clear that neither grade of reflux nor IVP finding serves as a method to detect subtle renal damage, and that renal disturbance occurs even in cases with reflux of low grade and normal IVP. It is necessary to evaluate both urinary ratio and renal ratio (renal size) in cases with completely damaged nephrons, because they show often normal urinary excretion rate of β2-MG.
