Approach Considerations
No particular diagnostic procedures are available or needed for most patients with toxicity from mushrooms containing muscimol or ibotenic acid.
Laboratory studies can be helpful in identifying complications of hallucinogenic mushroom abuse, which may include hepatotoxicity with repeated use, acute renal failure, and rhabdomyolysis. [32] Serum levels and urine tests for toxins such as muscarine, muscimol, and psilocybin are available but are rarely helpful or necessary in clinical practice. [33] They are more applicable to forensic investigations.
Chromatographic techniques (eg, thin-layer chromatography [TLC], gas-liquid chromatography [GLC], and high-pressure liquid chromatography [HPLC]) are available to detect ibotenic acid, muscimol, [34] and psilocybin, as well as other mushroom toxins (eg, amanitins, orellanine, muscarine, and gyromitrins). [35] However, these techniques are typically unavailable to general practitioners, being largely restricted to laboratories conducting research on these compounds.
If the diagnosis is uncertain, and if blunt head trauma is part of the differential diagnosis because of changes in mental status, plain computed tomography (CT) of the head is warranted before lumbar puncture is performed.
Identification of the mushroom by a mycologist is desirable. Gastric contents may be examined. A mycologist may be able to microscopically identify the spores recovered from the patient’s gastric contents.
Laboratory Studies
A complete blood count (CBC) should be obtained because some mushroom toxins (eg, gyromitrin) can cause hemolytic anemia.
Baseline liver function studies are indicated because possible ingestion of other toxic mushrooms (eg, those containing cyclopeptides) can cause hepatotoxicity.
Baseline renal function studies are indicated because some mushrooms are nephrotoxic, such as A smithiana and orelline mushrooms.
Evaluation for rhabdomyolysis should be considered if signs and symptoms warrant because some mushrooms (eg, Tricholoma equestre) may cause muscle toxicity.
A basic serum metabolic profile (sodium, potassium, chlorine, carbon dioxide, creatinine, glucose, and calcium) should be obtained to evaluate for fluid and electrolyte disturbances due to other offending ingestants.
Urine drug screening should be considered, especially if the patient has unexplained symptoms or behavioral changes, if suicidal intent, substance abuse or foul play is suspected, or if ingestion of unknown toxins is suspected. The patient’s urine may be analyzed for muscimol to confirm muscimol poisoning, but this test is not typically available in hospital laboratories.
Identification of Mushroom Specimens
Identification of the mushroom ingested is generally desirable. However, with hallucinogenic mushrooms, definitive identification is seldom necessary. Exact identification of the mushroom is achieved in fewer than 3% of cases.
Mushrooms in the ibotenic acid group (see the images below) are commonly found throughout the United States, Europe, and Asia. They are found in wooded areas, especially among conifer forests, in the spring and fall seasons of North America. The young specimens emerge with patches of membrane left covering the cap and forming a cup (volva) at the base. The mature specimens often have brilliant cap colors and delicate skirts and cups.
A muscaria can occur alone or in groups on the ground of forests, in grassy areas and lawns, and especially under trees. The cap is 5-30 cm in diameter and contains white warts. The stalk is white, frequently hollow, and often as long as 15-20 cm. A prominent volva is found at the bottom of the stalk, with numerous rings superiorly. The gills are free and white. The spores are also white. The appearance varies according to geographic location. Scarlet caps are most common in western North America, orange to yellow-orange caps in eastern North America.
Different types of mushrooms can be found in the same location, and reliance on a single sample can lead to false identification of the mushroom that was ingested. All mushrooms in the immediate vicinity of the ingestion site must be considered. When no specimen is brought in by a patient with a suspected mushroom ingestion, sending an experienced forager to the site to collect any mushrooms growing in the area might be helpful.
When mushroom specimens are obtained for identification, the entire mushroom should be dug up to preserve the architecture of the bulb, stem, and cap. (Keep in mind, however, that definitive identification should be made by an experienced mycologist rather than by a physician.)
To make a spore print, slice the mushroom stem from the cap very close to the gills, and lay the cap onto a piece of paper with the gills down. Make prints on black-and-white paper. These can be sent to the regional poison control center or its designee for analysis.
Whole mushrooms can be sent. Samples should include, if possible, the deeply rooted portion of the fungus, as well as the cap and gills. They should not be packaged in plastic or cloth, because they may decompose rapidly. Samples should be placed in a paper bag with an absorbant (eg, a piece of filter paper) to prevent condensation. Transporting the mushrooms in this way minimizes destruction of their natural architecture, discoloration of the cap or gills, and premature release of the spores. The mushrooms also must not be refrigerated or crushed.
The widespread availability of digital cameras enables rapid transmission of images of mushroom samples to mycologists over the Internet. Although it may not be possible to make a definitive identification via this method, it may be possible at least to rule out certain species. [29]
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Fly agaric (Amanita muscaria).
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Amanita pantherina.
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Amanita muscaria.
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Amanita muscaria var. guessowii with yellow cap surface, from Massachusetts.
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Amanita muscaria var. formosa sensu Thiers, from Oregon.
