Infectious Glomerulonephritis, One-Year-Follow-Up After Acute Kidney Injury (Aki) – A Case Report

Background: Post-Infectious Glomerulonephritis (PIG) is the most common cause of acute glomerulonephritis (AGN) in children and manifests clinically as nephritic syndrome. Pneumonia is rarely associated with the occurrence of AGN. PIG prognosis is usually benign, with complete recovery occurring in most cases. Hypocomplementemia is associated with a more severe disease course, namely, azotaemia and nephritic syndrome. Proteinuria persistency, even residual, might be a long-term predictive factor for chronic kidney disease.

Case Report: Four-year-old previously healthy girl with national immunization program up to date, was admitted to our paediatrics unit with right-lobe pneumonia complicated with acute renal injury. The urinalysis revealed haematuria (5-10 erit/uL), proteinuria (protein/creatine ratio 2,4 mg/mg) and leukocyturia. There was no acid-base imbalance. C3 levels were low (11,3 mg/dL, range 81-167), with normal C4 levels. After 24h of standard antibiotic therapy, hypertension, generalized oedema, oliguria and inspiratory bibasal crackles appeared. IV furosemide was initiated, with progressive clinical and analytical improvement, blood pressure and diuresis normalized in 48 hours. Five weeks after discharge, under no medication, she was asymptomatic and normotensive, without other abnormalities on physical examination. Renal function and inflammatory parameters were normal, and C3 levels improved (58,8 mg/dL, range 81-167 mg/dL). Microscopic haematuria and mild proteinuria (protein/creatinine ratio 0,33 mg/mg) were still present. Six months after this episode, there was no haematuria, C3 levels and the protein/creatinine ratio were normalised, but microalbuminuria, though residual, persisted (22,7 mg/g creatinine). One year after the acute episode, microalbuminuria returned to the normal range (<10 mg/g creatinine).

Conclusions: With this case presentation, the authors highlight the concomitant renal impairment associated with respiratory infection, namely pneumococcal pneumonia, an increasingly diagnosed form of infectious glomerulonephritis. It is important to reinforce the significance of follow-up to identify possible complications and prevent functional deterioration, even when the PIG has an overall favourable prognosis.