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

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.

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.

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 m² (IQR 13.3-43) at time of biopsy. Patients who had either a pre-biopsy eGFR < 35 ml/min/1.73 m² 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.

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.