767 - Methemoglobinemia in Children: Prevalence, Treatment and Outcome

The study objectives were to determine the prevalence of this disease in the pediatric population, describe the underlying etiology, and evaluate the medical management.

Design/Methods: This was a retrospective observational cohort study utilizing TriNetX ©, a multi-center electronic health record database, in children aged 0 to 18 years who had a methemoglobin level (MetHb) greater than 5% and had received treatment for it. We evaluated diagnostic, medication, laboratory, and procedural codes.

Results: Out of 6,324,523 children from 53 healthcare organizations, 98 (mean age 5.27 [SD 5.32] years) children had methemoglobin level > 5 %. Methemoglobinemia prevalence was 0.0015%. 6 (6%) subjects were diagnosed with congenital methemoglobinemia. Mean methemoglobin percent, hemoglobin level, methemoglobin level, functional Hb, pulse oximetry oxygen saturation and partial pressure of oxygen in arterial blood are presented in Table 1. The top two agents known to cause methemoglobinemia were present at a high frequency: lidocaine (16.3%) and dapsone (12.2%). Methylene blue was prescribed in 35 (35.7%) subjects. Subjects with MetHb levels greater than 20% had a higher frequency of methylene blue and Vitamin C prescription as compared to children with MetHb levels less than 20 % [75.8% versus 39.65%; p = 0.00096 and 5.8% versus 32.09 %; p= 0.02 respectively]. Glucose-6-phosphate dehydrogenase (G6PD) deficiency was diagnosed in 8 (8.2%) subjects and 11 (11.2%) subjects with no prior G6PD deficiency diagnosis were tested for it. Critical care services were required in 23 subjects, with 18 (78.26%) having a methemoglobin level less than 20% (p > 0.05). Subjects with functional Hb less than 7 g/dl had a higher percentage of critical care services and mechanical ventilation as compared to those with levels greater than 7 g/dl [41.6 % versus 24.32 %, p > 0.05 and 33.3 % versus 12.16%, p > 0.05 respectively], none were reported to have received methylene blue. Mortality was 6.1 %, and methemoglobin level in these patients was less than 20%.

Conclusion(s): Methemoglobinemia prevalence in children is low. A low frequency of G6PD testing children was performed despite hemolysis risk with methylene blue. Functional Hb calculation should be considered as subjects with levels less than 7 g/dL may require aggressive treatment for methemoglobinemia irrespective of the methemoglobin percent.