Urinary tract infection in a child — USMLE Step 2 CK MCQ

Correct answer: B — Start plasma exchange, glucocorticoids, and cyclophosphamide

Pulmonary hemorrhage, rapidly progressive crescentic glomerulonephritis, and linear glomerular-basement-membrane IgG establish anti-GBM disease. Treatment uses three complementary measures: plasma exchange removes circulating pathogenic antibody, glucocorticoids rapidly suppress inflammation, and cyclophosphamide suppresses further antibody production. This is a time-sensitive organ-threatening syndrome, so therapy should not be deferred after the diagnosis is established. Glucocorticoid monotherapy does not remove antibody or adequately prevent continued production. Rituximab may be considered in selected refractory situations but is not standard initial monotherapy. Hemodialysis provides renal support when indicated but does not treat alveolar hemorrhage or the autoimmune process. Infection should be evaluated and treated when present, yet bilateral alveolar hemorrhage with biopsy-proven linear IgG is not an indication to substitute antibiotics for immunosuppression. Prognosis for renal recovery is worse with advanced dialysis-dependent disease and extensive chronic injury, but active pulmonary hemorrhage remains a strong indication for urgent disease-directed treatment.

Reference: National Institute of Diabetes and Digestive and Kidney Diseases. Anti-GBM (Goodpasture's) Disease. https://www.niddk.nih.gov/health-information/kidney-disease/glomerular-disease/anti-gbm-goodpastures-disease