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Methemoglobinemia associated with loxoscelism
O C Barretto1, D M De Cillo, K Nonoyama
1Laboratório de Pesquisas Hemotológicas-LIM/31 Faculdade de Medicina da Universidade de São Paulo, Brasil.
Revista Do Instituto De Medicina Tropical De Sao Paulo
|January 1, 1990
Summary
Loxosceles spider bites can cause methemoglobinemia in 54% of patients, likely due to in vivo venom metabolism. Further research is needed as crude venom did not induce this condition in vitro.
Area of Science:
- Toxicology
- Hematology
- Dermatology
Background:
- Cutaneous loxoscelism, a condition caused by Loxosceles spider bites, can present with various systemic effects.
- Methemoglobinemia, a condition characterized by elevated levels of methemoglobin in the blood, has been anecdotally associated with Loxosceles envenomation.
Purpose of the Study:
- To investigate the incidence and potential mechanisms of methemoglobinemia following Loxosceles bites.
- To determine if Loxosceles venom directly induces methemoglobinemia in vitro.
Main Methods:
- Serum haptoglobin, lactic dehydrogenase, erythrocyte glucose-6-phosphate dehydrogenase, glutathione reductase, glutathione peroxidase, methemoglobin, bilirubin, and reticulocytes were analyzed in 25 patients with cutaneous loxoscelism.
- Blood samples from a healthy individual and a patient with methemoglobinemia were incubated with Loxosceles gaucho venom and other agents to assess methemoglobin formation in vitro.
Main Results:
- No hemolysis was detected in patients.
- Methemoglobinemia was observed in 54% of patients, with varying levels.
- In vitro incubation with Loxosceles venom did not induce methemoglobinemia, although methemoglobin reductase activity decreased in all samples by day 25.
Conclusions:
- The findings suggest that methemoglobinemia in loxoscelism patients likely results from in vivo venom metabolism rather than direct venom action.
- Further studies are warranted to elucidate the precise mechanisms underlying venom-induced methemoglobinemia.