Influenza A Presenting as Life-Threatening Rhabdomyolysis and Acute Kidney Injury Requiring Renal Replacement Therapy.

Influenza A is primarily a respiratory pathogen but may rarely cause severe extrapulmonary manifestations, including myositis, rhabdomyolysis, and acute kidney injury (AKI). Recognition of this complication is often delayed because respiratory symptoms may be absent or overshadowed by systemic manifestations. We present a case of a previously healthy 31-year-old man who presented with fever, generalized myalgia, oliguria, and dark urine. Laboratory evaluation demonstrated extreme rhabdomyolysis with a peak creatine kinase (CK) concentration of 468,130 U/L, severe transaminitis consistent with severe skeletal muscle injury, myoglobinuria, electrolyte abnormalities, and rapidly progressive AKI. Extensive evaluation excluded alternative infectious and noninfectious etiologies. Respiratory viral polymerase chain reaction testing confirmed influenza A infection. Despite aggressive fluid resuscitation and metabolic correction, worsening renal dysfunction necessitated six sessions of intermittent hemodialysis. Following treatment with oseltamivir, renal replacement therapy, and supportive care, the patient experienced progressive biochemical recovery and was discharged without ongoing dialysis requirements. Influenza-associated rhabdomyolysis is uncommon in adults, and severe cases requiring renal replacement therapy remain rare. Proposed mechanisms include direct viral invasion of myocytes, cytokine-mediated muscle injury, and systemic inflammatory stress. This case was characterized by an exceptionally high CK concentration of 468,130 U/L. It highlights the potential for fulminant muscle injury even in the absence of prominent respiratory manifestations. Influenza A should be considered in patients presenting with unexplained rhabdomyolysis, myoglobinuria, and AKI during the influenza season. Early antiviral therapy, aggressive supportive care, and timely initiation of renal replacement therapy may be lifesaving.