History: History of exposure is of utmost importance; without it, diagnosing mushroom or orellanine poisoning is unlikely. History of mushroom ingestion may be very remote, particularly with orellanine, since early gastrointestinal symptoms may not be severe enough for patients to seek medical attention. Patients with symptoms of renal failure may not present until 1-3 weeks after exposure. The emergency physician should routinely inquire about mushroom ingestion whenever a patient presents with gastroenteritis. A shorter latent period before onset of illness suggests more severe toxicity and greater risk of more severe renal failure than delayed onset of illness. Improvement in renal injury may occur within several weeks to months; however, renal injury may last months to years and patient may require chronic hemodialysis or renal transplant.

Important details of ingestion include the following:

Time of ingestion and, most importantly, time from ingestion to onset of symptoms (onset typically delayed)

Amount ingested

If co-ingestion of other types of mushrooms occurred

If other people ingested the same mushrooms and, if so, their reactions or symptoms

Where the mushrooms were picked
Gastrointestinal symptoms
Nausea and vomiting

Abdominal pain

Diarrhea or constipation

Symptoms are usually mild and observed 24-48 hours postingestion.
Renal symptoms
Flank pain

Intense thirst (sometimes described as burning)

Polyuria or oliguria
Anuria (rare)
Acute renal failure may occur anytime from 36 hours to 2 weeks postingestion.
Systemic symptoms
Anorexia
Chills
Myalgias
Dysgeusia
Rash
Neurologic
Somnolence
Lassitude
Headache
Paresthesias
Tinnitus
Seizures (rare)
Physical: Patients with orellanine induced renal failure may have a paucity of findings on physical examination.

Assess volume status
With anorexia and polyuria, volume depletion may be present.
With anuric renal failure, volume overload is possible.
Neurologic
With modest degrees of renal dysfunction, mental status may be relatively preserved.
With more advanced renal failure, depressed mentation, confusion, or coma may occur.
Myoclonus and asterixis suggest uremia in this setting.
Gastrointestinal: By time of presentation, abdominal symptoms may have resolved.
Renal: Flank tenderness may be present.
Other findings: Signs of uremia (eg, pericarditis, pleuritis, volume overload) may be present.
Causes: Risk factors include ingesting mushrooms of the Cortinarius group that contain the renal toxin orellanine. Severity is partially proportional to amount of toxin ingested.