Biomarkers of histologic severity in children with severe or atypical acute post-streptococcal glomerulonephritis.

Background: Acute post-streptococcal glomerulonephritis (APSGN) is a common cause of acute kidney injury (AKI) in children; however, in a small subgroup, the presentation is one of rapidly progressive glomerulonephritis (RPGN) deteriorating kidney function associated with severe oligo-anuria or a mixed nephritic-nephrotic picture. This study reviewed potential clinical and laboratory factors which may assist the treating clinician to identify patients at high risk of severe disease.

Methods: All kidney biopsies for APSGN performed between 1996 and 2020 were obtained from a departmental biopsy database. Clinical and laboratory data were extracted from the patients' clinical records. Kidney biopsies were reviewed and scored independently by a renal histopathologist.

Results: Thirty of 53 (56.6%) patients had stage 3 AKI at initial presentation with a median estimated glomerular filtration rate (eGFR) 27 (IQR 11-41), falling to 20 ml/min/1.73 m (IQR 13.3-43) at time of biopsy. Patients who had either a pre-biopsy eGFR < 35 ml/min/1.73 m or a ≥ 25% fall in eGFR between admission and biopsy were more likely to have glomerular crescents (p = 0.004). Multivariate regression analysis and receiver operating curve showed the pre-biopsy eGFR most accurately predicted glomerular crescents (p = 0.047, ROC 0.757). There were no significant predictors of nephrotic proteinuria or nephrotic syndrome during the acute phase.

Conclusions: Severe APSGN is associated with a pronounced reduction in eGFR. Calculation of eGFR in this small group of patients may assist in identifying which patient should have an urgent kidney biopsy to facilitate a more accurate clinical diagnosis and management plan.