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.

Dapsone induced methemoglobinemia : Intermittent vs continuous intravenous methylene blue therapy.

OBJECTIVE: The study compares the decline in blood methemoglobin (MetHb) level in children of dapsone intoxication treated with intermittent and continuous methylene blue therapy. METHODS: Eleven children with history of accidental dapsone ingestion and suggestive clinical features of dapsone intoxication were studied. Patients were randomized into two groups: Gr I (n=5) received intermittent methylene blue therapy, while Gr II (N=6) as continuous infusion. The dose of methylene blue was same in both groups. MetHb level in blood was assessed by spectrophotometer at admission and thereafter 12hrly up to 72 hrs. The decline in MetHb was statistically analyzed with student t-test. RESULTS: Six patients had history of seizure and altered sensorium. Severe anemia was observed in 2 patients. The mean levels of MetHb in Gr II was statistically significant after 12, 24, 36, 48 and 72 hrs of methylene blue therapy as compared to Gr I. CONCLUSION: Continuous I.V methylene blue therapy causes significant decline in MetHb level and is more effective in treatment of methemoglobinemia as compared to intermittent regimen.

Optical coherence tomographic evaluation of macular infarction following dapsone overdose.

A 16-year-old girl had decrease in vision following dapsone overdose. This case demonstrated optical coherence tomography (OCT) evaluation of macular infarction following dapsone poisoning. OCT showed characteristic serial changes as Stage 1: Cystic macular edema, Stage 2: Resolving cystic change and Stage 3: Foveal atrophy. Hence, OCT could show the progression of foveal atrophy from cystic macular edema following dapsone poisoning.

Clinical and laboratory parameters in dapsone acute intoxication

Objetivo: Definir a gravidade da intoxicaçäo aguda por dapsona (DDS) - uma ocorrência médica näo usual - usando parâmetros clínicos e laboratoriais. Métodos: Foram estudados 274 pacientes intoxicados por DDS, divididos em 4 grupos etários; as idades variaram de um mês a 50 anos. A avaliaçäo clínica foi efetuada por meio de um questionário e correlacionada com parâmetros laboratoriais. A metemoglobinemia (MHbp) e a dapsonemia (DDSp) foram analisadas por métodos espectrofotométricos. Resultados: O sinal clínico mais prevalente da intoxicaçäo foi a cianose, presente em 65,7 por cento dos pacientes e em 100 por cento das crianças menores de 5 anos. A intoxicaçäo grave, definida laboratorialmente, de acordo com a MHb ocorreu em 56,2 por cento dos pacientes e, de acordo com a DDSp, em 58 por cento. A intoxicaçäo foi grave, de acordo com a DDSp, quando houve a ingestäo mediana de 20 comprimidos (100 mg cada) e, de acordo com a MHbp, quando a ingestäo foi de 7,5 comprimidos. A mediana de MHbp foi de 38 por cento da Hb total. A correlaçäo entre MHbp e a DDSp foi significativa (n=144, r=0,32, p<0,05). Observou-se uma correlaçäo negativa entre a MHbp e o tempo decorrido da intoxicaçäo (n=124, r=0,34, p<0,001). Correlaçäo negativa, entre o DDSp e o tempo decorrido da intoxicaçäo, também foi observada (n=63, r=0,35, p<0,0001). Conclusöes: A gravidade da intoxicaçäo representada pelos valores da dapsonemia, determinada pela análise longitudinal, demonstrou uma associaçäo significativa entre metemoglobinemia e o tempo decorrido da ingestäo (t), de acordo com a equaçäo: Dapsonemia = 12,9256-0,0682.t + 0,234.metemoglobinemia

Peripheral neuropathy and haemolytic anaemia with cherry red spot on macula in dapsone poisoning.

A young female presented with haemolytic anaemia due to dapsone overdosage. She developed peripheral neuropathy and marked visual impairment with a cherry red spot on the macula, possibly due to toxic retinal vascular damage; both these resolved in due course. Cherry red spot due to dapsone poisoning has not been reported previously.