Case of methemoglobinemia in an infant with cyanosis

Methemoglobinemia refers to a group of hemoglobinopathies which characterized by an increase of the hemoglobin (Hb) amount, in which oxidation of ferrous iron to ferric iron is observed with the loss of the ability to reversibly bond with oxygen and the development of hemic hypoxia. Cyanosis is the most common symptom of methemoglobinemia and is the reason for the differential diagnosis of cardiovascular and respiratory diseases. Timely determination of the cause of cyanosis in a newborn can be a difficult task. By origin, cyanosis in children at birth and in the first weeks of life is cardiac, respiratory, cerebral, metabolic, and hematological. The prognostic value of cyanosis is different for different diseases. Pronounced and persistent cyanosis in diseases of the lungs and heart indicates a high degree of respiratory or heart failure and prognostic unfavorable. Most of the causes of acute cyanosis is an immediate threat to the life of the patient. Prolonged tissue hypoxia in patients with persistent cyanosis leads to the development of secondary erythrocytosis, an hematocrit increase, blood viscosity, which worsens the microcirculation in tissues, aggravating the deficit of tissue respiration. If cyanosis is detected in infants, differential diagnosis should include hemoglobinopathies, in particular, methemoglobinemia. A carefully collected medical history, the exclusion of all possible causes of cyanosis and hypoxemia, and the assessment of methemoglobin in the blood allow a timely diagnosis. The purpose of the article is to describe the clinical observation of methemoglobinemia in an infant with a detailed discussion of the characteristics of the case.