Methemoglobinemia-Induced Acute Kidney Injury

Abstract

IntroductionMethemoglobinemia refers to the presence of increased levels of methemoglobin (Fe3+) in the blood. Methemoglobinemia can cause cyanosis, dyspnea, fatigue, seizure, arrhythmia, coma, and even death. Although methemoglobinemia is shown to cause acute kidney injury in experimental settings, human case reports are exceedingly rare. In addition, morphological features of methemoglobinemia-induced renal disease in humans remain undefined.Case PresentationA 76-year-old man with a history of chronic obstructive pulmonary disease underwent bronchoscopy following local anesthesia with a benzocaine spray. The patient developed benzocaine-induced methemoglobinemia and acute renal failure. Urinalysis disclosed numerous dysmorphic erythrocytes, erythrocyte casts, and granular casts. Urine protein excretion was approximately 1.1 g/day. Serologic tests were negative. Renal biopsy demonstrated minor glomerular abnormalities, severe acute tubular necrosis, and numerous erythrocyte casts in the tubules. Despite supportive care, renal function deteriorated necessitating hemodialysis. Four months later, the patient remained on hemodialysis. To exclude a superimposed pathology, renal biopsy was repeated and showed numerous erythrocyte casts in the tubules and severe tubular damage.ConclusionMethemoglobinemia can cause acute kidney injury in humans. Morphological features resemble those observed in methemoglobin-induced acute kidney injury in experimental settings. This case calls for a heightened awareness of potential adverse effects of methemoglobinemia on renal function.