Resumo

CARVALHO, Claúdia et al. Methemoglobinemia: case report and review. Arq Med [online]. 2011, vol.25, n.3, pp.100-106. ISSN 2183-2447.

Methemoglobin is a derivative of hemoglobin characterized by the presence of iron in the ferric state, unable to bind oxygen. Methemoglobinemia occurs due to either increased methemoglobin production or decreased reduction and results in a functional anemia that may be fatal. Young and healthy patients who are not anaemic usually have no symptoms if methemoglobin levels are below 15%. levels of 20-30% may cause mental status changes, headache, fatigue, dizziness, and syncope. Levels greater than 50% may result in dysrhythmias, seizures, coma, and death. Acquired methemoglobinemia is a fairly common, yet often unrecognized condition and commonly prescribed drugs are usually implicated. Methemoglobinemia should be considered in the presence of cyanosis despite a normal partial arterial pressure of oxygen (pa O2) or when disparity between different techniques to measure oxygen saturation, namely pulse oximetry and arterial blood gases is detected. Treatment options depend mostly of methemoglobin levels and the severity of symptoms. In mild cases the interruption of the offender may suffice but in symptomatic patients blue methilene and red blood cells transfusion should be considered. Exsanguination and hyperbaric oxygen have been used in exceptionally severe cases. Methemoglobinemia is a potencially fatal condition that can be reverted once diagnosed and treated. We describe a case of methemoglobin secondary to dapsone in a patient infected with HIV. physiopathology, etiology, diagnosis and treatment of methemoglobinemia are reviewed.

Palavras-chave : methemoglobin; dapsone; hiv.

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