A 10-year retrospective study of patients with acquired methemoglobinemia: causative agents, clinical characteristics, and outcomes
Issued Date
2026-01-01
Resource Type
ISSN
15563650
eISSN
15569519
Scopus ID
2-s2.0-105033661354
Journal Title
Clinical Toxicology
Rights Holder(s)
SCOPUS
Bibliographic Citation
Clinical Toxicology (2026)
Suggested Citation
Tansuwannarat P., Bualerd P., Rittilert P., Tongpoo A., Trakulsrichai S. A 10-year retrospective study of patients with acquired methemoglobinemia: causative agents, clinical characteristics, and outcomes. Clinical Toxicology (2026). doi:10.1080/15563650.2026.2631791 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/115976
Title
A 10-year retrospective study of patients with acquired methemoglobinemia: causative agents, clinical characteristics, and outcomes
Corresponding Author(s)
Other Contributor(s)
Abstract
Introduction: Acquired methemoglobinemia results from exposure to various oxidizing agents; however, data remain limited in Asia, including Thailand, where certain drugs and agricultural chemicals are widely used. Local epidemiologic data are essential for early recognition and clinical management. Methods: A 10-year retrospective cohort study of poison center–identified cases of acquired methemoglobinemia (2013–2022). Patients were included if they had a methemoglobinemia (concentration >3%) or a characteristic oxygen saturation gap with subsequent clinical recovery. Demographic, exposure, clinical, treatment, and outcome data were collected, and factors associated with mortality were analyzed using a multivariate binary regression model. Results: Among 169 patients (median age 43 years; 59.17% male), the leading causes were dapsone (30.18%) and propanil (27.22%), followed by herbal and food-related agents. In some patients (19.53%), the specific oxidizing agents could not be identified. Neurological, cardiovascular, and hematologic manifestations occurred in 24.26%, 33.73%, and 40.24% of cases, respectively. The median and highest methemoglobin concentrations were 11.50% and 48.85%. Most patients (88.76%) were hospitalized, with 40.24% requiring admission to the intensive care unit. Treatments included administering oxygen (95.86%), intravenous fluids (81.07%), and methylthioninium chloride (31.36%; median dose: 1 mg/kg), as well as blood transfusion (43.20%) and intubation (33.73%). Complications occurred in 29.59% of cases, most commonly sepsis and pneumonia. The mortality rate was 11.24%. Discussion: Mortality was driven not only by the severity of methemoglobinemia but also by systemic complications that occurred during hospitalization. Shock at presentation was the sole prognostic factor and likely reflected severe concurrent complications rather than a direct effect of methemoglobinemia, emphasizing the prognostic importance of early systemic illness. Early recognition, prompt resuscitation, and timely management of complications are essential for improving survival rates. Conclusions: Acquired methemoglobinemia is most often caused by dapsone and propanil. Shock at presentation may prognosticate a fatal outcome. Early diagnosis, timely therapy, and aggressive management of systemic complications are required to improve the patients’ clinical outcomes.