Renal Biopsy in Children-Effect on Treatment Decisions: A Single-Center Experience

Clinical Predictors of Steroid Resistance in Childhood Nephrotic Syndrome

We aimed to evaluate the clinical parameters, histopathological findings of nephrotic syndrome (NS) patients, and independent factors predicting steroid resistance in a single tertiary center. One hundred and sixty-two children (57 girls and 105 boys) with NS who were followed between 1998 and 2018 were analyzed in this retrospective cohort. The median (interquartile range; range) age and follow-up time were 4.9 (5.7; 0.1-16.8) and 5.5 (5.4; 0.1-20.3) years. A total of 82.7% of the patients were steroid-sensitive nephrotic syndrome (SSNS) and 17.3% were steroid-resistant nephrotic syndrome (SRNS). The median age at first presentation was lower in the SSNS group (P = .002). The most common histopathological findings were focal segmental glomerulosclerosis (FSGS) and minimal change disease (MCD). Hypertension and macroscopic and microscopic hematuria were higher in the SRNS group (P < .001). The age and microscopic hematuria were independent risk factors for steroid resistance (P = .019 and P = .002, respectively). Complement 3 (C3) was evaluated in 148 patients and found low in 7 patients who were subsequently diagnosed as membranoproliferative glomerulonephritis. There is still no better clinical predictor for steroid response than late age of onset and microscopic hematuria. Hypertension may also give a hint for potential steroid resistance.

Role of Urinary Biomarkers (Transforming Growth Factor β1, Neutrophil Gelatinase-Associated Lipocalin, and Cystatin C) as a Prognostic Factor of Renal Outcome in the Posterior Urethral Valve

Background

The urinary biomarker response precedes the appearance of any renal structural or functional derangement. Transforming growth factor-β1 (TGF-β1), neutrophil gelatinase associated lipocalin (NGAL), and Cystatin C (CysC) can act as the early prognostic markers in posterior urethral valve (PUV) patients.

Aim

To compare the urinary levels of TGF-β1, NGAL, and CysC between PUV cases and age matched controls and to correlate these with renal structural and functional parameters.

Materials and Methods

This prospective study included children with PUV diagnosed using the standard investigations and an equal number of age-matched controls with nonurological problems. For the study subjects, the urinary samples were collected at three different time points (pre- and postoperatively at 3 and 6 months), whereas for controls, only single-voided samples were studied. The urinary levels of TGF-β1, NGAL, and CysC were estimated by the standardized techniques using the ELISA kits. Statistical methods were used to drive the comparisons between cases and controls.

Results

Fifteen children with a median age of 10 (5-48) months were enrolled in each of the two groups. The mean uTGF-β1 in the case group was significantly higher at all three time points (43.20 ± 6.13 pg/ml, 43.33 ± 11.89 pg/ml and 40.71 ± 9.01 pg/ml) as compared to the control group (29.12 ± 8.31 pg/ml) (P ≤ 0.001). The median uNGAL in the case group was also higher (17.78 ng/ml, 2.35 ng/ml and 2.536 ng/ml) as compared to the control group (1.31 ng/ml). However, the difference was significant only preoperatively (P = 0.02). The median uCysC in case group was similarly higher (0.347 μg/ml, 0.439 μg/ml, and 0.382 μg/ml) than the control group (0.243 μg/ml) (P > 0.05). Serum creatinine in the case group (0.49 mg/dl) showed no significant rise above that of control (0.24 mg/dl). A cutoff value of uTGF-β1 = 36.55 pg/ml (P < 0.001), uNGAL = 0.879 ng/ml (P = 0.02), and uCysC = 0.25 μg/ml (P = 0.22) was found to be associated with renal damage in PUV. A significant correlation was found between uNGAL and S. creatinine at 3 months (r = 0.43, P = 0.017) and 6 months (r = 0.47, P = 0.08).

Conclusion

The elevated uTGF-β1, a decline in uNGAL and an increase in uCysC suggests ongoing inflammation, improvement in hydronephrosis and a prolonged proximal tubular dysfunction in PUV patients, respectively.

Percutaneous kidney biopsies in children: a 24-year review in a tertiary center in northern Portugal

INTRODUCTION

Percutaneous kidney biopsy (KB) is crucial to the diagnosis and management of several renal pathologies. National data on native KB in pediatric patients are scarce. We aimed to review the demographic and clinical characteristics and histopathological patterns in children who underwent native percutaneous KB over 24 years.

METHODS

Retrospective observational study of patients undergoing native percutaneous KB in a pediatric nephrology unit between 1998 and 2021, comparing 3 periods: period 1 (1998-2005), period 2 (2006-2013), and period 3 (2014-2021).

RESULTS

We found that 228 KB were performed, 78 (34.2%) in period 1, 91 (39.9%) in period 2, and 59 (25.9%) in period 3. The median age at KB was 11 (7-14) years. The main indications for KB were nephrotic syndrome (NS) (42.9%), hematuria and/or non-nephrotic proteinuria (35.5%), and acute kidney injury (13.2%). Primary glomerulopathies were more frequent (67.1%), particularly minimal change disease (MCD) (25.4%), IgA nephropathy (12.7%), and mesangioproliferative glomerulonephritis (GN) (8.8%). Of the secondary glomerulopathies, lupus nephritis (LN) was the most prevalent (11.8%). In group 1, hematuria and/or non-nephrotic proteinuria were the main reasons for KB, as opposed to NS in groups 2 and 3 (p < 0.01). LN showed an increasing trend (period 1-3: 2.6%-5.3%) and focal segmental glomerular sclerosis (FSGS) showed a slight decreasing trend (period 1-3: 3.1%-1.8%), without statistical significance.

CONCLUSIONS

The main indication for KB was NS, which increased over time, justifying the finding of MCD as main histological diagnosis. LN showed an increase in incidence over time, while FSGS cases did not increase.