BACKGROUND: Despite the kidney being affected by diphtheria exotoxin, the extent of acute kidney injury (AKI) and its possible impact on outcomes remain unknown. This study examined the incidence, risk factors, and outcomes of AKI in children with diphtheria. METHODS: This was a prospective cohort study of confirmed diphtheria managed from July 1, 2023, to April 30, 2024, at a health facility in Nigeria. We obtained data on clinical and laboratory features and treatments received. AKI was defined using Kidney Disease: Improving Global Outcomes (KDIGO) criteria. RESULTS: We included 237 children with a median [interquartile range] age of 7.0 [4-10] years. Using KDIGO, 139 (58.6%) had AKI [stage 1:88 (37.1%)
stage 2: 18 (7.6%)
and stage 3: 33 (13.9%)]. Variables associated with AKI included age, sore throat, inability to swallow, difficulty breathing, nasal blockade, hypoxemia, nasal discharge, pallor, abnormal chest findings, hospitalization duration, vaccination status, white blood cells, lymphocytes, platelets, serum bicarbonate, sodium and potassium, and treatments received, CONCLUSION: There is a high incidence of AKI among children with diphtheria and increased odds of death. Factors that predicted AKI included younger age, oxygen therapy, and medications (ibuprofen and dexamethasone).