A 25 y.o. outdoorsman in Oregon returned from a camping trip with diarrhea.

He subsequently presented two days later with a bluish discoloration of the skin. His O2 sat is 80%. What could be wrong?

The patient has methemoglobinemia.  In this case it is from eating false morel mushrooms on his camping trip.  Of the 5,000 mushroom species hunted by foragers only 2% are poisonous  to humans but false morel  (Gyromitra and Verpa ) are known to cause poisoning.  They are eaten in Europe and the preparation seems important in decreasing the toxicity.  Raw mushrooms are poisonous; those rinsed several times in water and those that are dried  or cooked seem less likely to contain toxin.

 Spring is morel season in Missouri and across the country and the season for false morels as well.

distribution of false morel mushrooms in the US

The false morel mushrooms:  Gyrometra esculenta  or Verpa species are often mistaken for a true morel mushroom. They produce gyromitrin which is metabolized into monomethylhydrazine.  Hydrazines  produce a functional pyridoxine deficiency( B6) because they interfere with the production of pyridoxal phosphate preventing the synthesis of GABA.   Excitation results in the central nervous system which can cause seizures. B6 deficiency can also lead to impaired hemoglobin synthesis and methemoglobinemia may result.

METHEMOGLOBINEMIA

Methemoglobinemia  causes a pulse ox to read 82-86% even if the PaO2 is high. An oxygen saturation in the 80s should not generally cause cyanosis.  A patient’s blood dropped on a white gauze will stay brown and not pick up oxygen from the air and turn red.  Methylene blue can be given unless the pt is G6PD deficient or on a MAO inhibitor because it can precipitate serotonin syndrome.

Clinically, Gyrometra ingestion  presents with a GI prodrome followed by liver, kidney and central nervous system injury although it is rarely fatal. The treatment is supportive care and  administration of pyridoxine if seizures occur. Methylene blue is used if the patient is symptomatic or has a methemoglobin level greater than 30%.

Dave’s sushi in Bozeman Montana where 60 people had documented mushroom poisoning and two died in 2023..

FUN FACTS

In Sweden the poisoning is relatively frequent because the mushroom is widely available in the country.

INH causes a pyridoxine deficiency similar to the hydrazine in false morels and is also treated with B6.

Hydrazine was a component of rocket fuel  in WW II. It is used in spacecraft as a propellant. Currently, most exposures to hydrazines  are associated with military exposures. 

In addition to mushrooms, benzocaine and anbesol have been reported as causes of methemoglobinemia.

Morels are common in Missouri in the spring and sell for $50 a pound

Our patient recovered without treatment.

 MushroomObserver.org

Farkas J. Methemoglobinemia. The Internet Book of Critical Care.  Oct 2,2021

Horowitz K, Kong E, Regina A, et al.  Gyromitra mushroom toxicity

Arłukowicz-Grabowska M, Wójcicki M, Raszeja-Wyszomirska J, Szydłowska-Jakimiuk M, Piotuch B, Milkiewicz P. Acute liver injury, acute liver failure and acute on chronic liver failure: A clinical spectrum of poisoning due to Gyromitra esculenta. Ann Hepatol. 2019 May-Jun;18(3):514-516

Pyysalo H, Niskanen A. On the occurrence of N-methyl-N-formylhydrazones in fresh and processed false morel, Gyromitra esculenta. J Agric Food Chem. 1977 May-Jun;25(3):644-7.

Biggs D, Castillo D. Warm & Blue: a case of methemoglobinemia. JETem DOI: https://doi.org/10.21980/J8591MIssue 4:1(No subject)

https://foodpoisoningbulletin.com/2023/fda-releases-morel-advisory-after-daves-sushi-illnesses/