Metahemoglobinemia, una entidad de diagnóstico complejo. Reporte de un caso

Methemoglobinemia is a rare condition with serious consequences if not diagnosed. We report the case of a 64-year-old woman with a history of allergy to sulfa drugs and a recent diagnosis of a small vessel vasculitis (ANCA-p) who started induction therapy with corticosteroids and rituximab. Due to the need for infectious prophylaxis, and considering her history, dapsone was administered instead of cotrimoxazole after ruling out glucose-6-phosphate dehydrogenase deficiency. During the admission to the hospital for her second dose of rituximab, and while being asymptomatic, she persistently presented a pulse oximetry ≪ 90% despite the administration of O2. Therefore, the infusion was postponed to study the patient. The arterial gasometric study by direct potentiometry revealed an O2 saturation of 98%, with a saturation gap > 5%. Considering the use of dapsone, a methemoglobinemia was suspected and confirmed by co-oximetry (methemoglobinemia 9%). Dapsone was suspended and one week later, her methemoglobinemia was absent.

Metahemoglobinemia inducida por dapsona: presentación de un caso pediátrico / Methemoglobinemia due to Dapsone: a pediatric case report

La metahemoglobinemia es una patología caracterizada por la presencia de altas concentraciones de metahemoglobina en sangre. Esta es una forma oxidada de la hemoglobina, muy afín al oxígeno, que es incapaz de cederlo a los tejidos. Es una entidad poco frecuente, con baja sospecha diagnóstica. Aunque puede ser congénita en recién nacidos con cianosis, es más frecuente la adquirida por fármacos y tóxicos. En la Argentina, no se conoce la incidencia real de esta patología. El objetivo es comunicar un caso de metahemoglobinemia en una paciente pediátrica que ingresó al Hospital Magdalena V. de Martínez con cianosis en la cara y las extremidades, en mal estado general, con el antecedente de ingesta de varios comprimidos de dapsona, y se constató concentración sérica de metahemoglobina del 35%. El tratamiento consistió en la administración endovenosa de azul de metileno. Su evolución fue favorable.

Methemoglobinemia is a condition characterized by a high blood concentration of methemoglobin. Methemoglobinemia is a disorder that occurs when hemoglobin in the blood is oxidized to form methemoglobin, rendering it unable to transport oxygen. Although it can be congenital in cyanotic newborn, it is more often an adverse medication effect. The aim is to report a pediatric methemoglobinemia case, assisted in Magdalena V. de Martínez Hospital, with cyanosis in face and limb, in poor condition, that consumed dapsone accidentally. Her methemoglobin concentration was 35%. Intravenous methylene blue was administered with favorable outcome.

A case of methemoglobinemia after ingestion of an aphrodisiac, later proven as dapsone

Methemoglobin (MetHb) is an oxidation product of hemoglobin in which the sixth coordination position of ferric iron is bound to a water molecule or to a hydroxyl group. The most common cause of acquired MetHb-emia is accidental poisoning which usually is the result of ingestion of water containing nitrates or food containing nitrite, and sometimes the inhalation or ingestion of butyl or amyl nitrite used as an aphrodisiac. We herein report a case of MetHb-emia after ingestion of an aphrodisiac, later identified as dapsone by gas chromatograph/mass selective detector (GC/MSD). A 24-year old male was admitted due to cyanosis after ingestion of a drug purchased as an aphrodisiac. On arterial blood gas analysis, pH was 7.32, PaCO2 26.8 mmHg, PaO2 75.6 mmHg, and bicarbonate 13.9 mmol/L. Initial pulse oxymetry was 89%. With 3 liter of nasal oxygen supplement, oxygen saturation was increased to 90-92%, but cyanosis did not disappear. Despite continuous supplement of oxygen, cyanosis was not improved. On the fifth hospital day, MetHb was 24.9%. Methylene blue was administered (2 mg/kg intravenously) and the patient rapidly improved. We proved the composition of aphrodisiac as dapsone by the method of GC/MSD.

Metahemoglobinemia adquirida por intoxicación con dapsona: presentación de un caso / Acquired metahemglobinemia by dapsone intoxication

Presentamos un caso de Metahemoglobinemia adquirida por la ingesta de 40 comprimidos de Dapsona, con intención suicida, produciéndole a la paciente una cianosis periférica marcada y deterioro del sensorio; se realizó tratamiento con Azul de Metileno y Acido Ascórbico, registrándose cifras posterapéuticas de Metahemoglobinemia de 19 por ciento (valores normales hasta 2 por ciento). Teniendo buena respuesta clínica, con evolución favorable, sin secuelas posteriores

Metahemoglobinemia en lactante pequeños / Methemoglobinemia in small infants

Se analizaron 40 casos consecutivos asistidos durante los dos últimos años, en el Hospital de Niños "Sor María Ludovica" de La Plata, que presentaron metahemoglobinemia (MHb). El 75% de los casos eran menores de 3 meses de vida. El motivo de consulta fueron manifestaciones gastrointestinales (diarrea, vómitos) en el 80% de los casos, cianosis en 17%, enfermedad respiratoria en el 12% y signos neurológicos en el 10%. Analizando los datos se vio que el 70% de los niños no tenían en sus hogares ningún servicio sanitario. El valor medio de MHb fue de 2,1 g/dl (rango 0,4-5,5 g/dl). Todos los niños, con excepción de uno, habían sido destetados. El 100% de los casos fue tratado exitosamente con vitamina C, como única medicación para su MHb