How to tell White webcap from Fool's webcap

It contains orellanine (Cortinarius orellanus contains the highest concentrations among webcaps), as well as the related compounds orelline and orellinine. Orellanine is a nephrotoxin that destroys the cells of the kidneys' proximal tubules through oxidative stress. It accumulates in the kidneys and produces symptoms slowly.

Its unique feature is a record delay of symptoms: in a review of 90 described poisonings (Danel et al., 2001), digestive upset usually appeared on the third day and signs of kidney damage on the eighth or ninth, occasionally even later. Because of this delay: people don't link their worsening condition to a mushroom eaten a week earlier, by then several portions may already have been eaten, medical help comes late — when the kidneys are already badly damaged, activated charcoal and gastric lavage are no longer effective.

Clinical phases:

Phase 1 (from day 2, most often days 3-7): thirst, dry mouth, headache, nausea, lower back (kidney) pain, mild gastroenteritis. The symptoms are often written off as a cold or food poisoning.

Phase 2 (days 7-14): oliguria (reduced urination), then anuria (no urine at all). Rising creatinine and urea in the blood, hyperkalemia. This is the phase of full-blown acute kidney failure.

Phase 3 (day 14+): either recovery of kidney function (partial, with scarring), or progression to chronic kidney failure requiring lifelong hemodialysis or a kidney transplant.

Deaths have been described (for instance in a mass poisoning in Poland), but the more common outcome is chronic kidney failure: in the review by Danel et al. (2001) it developed in about half of the cases.

Treatment: there is NO specific antidote. Symptomatic: hemodialysis to remove toxins and support the kidneys, infusion therapy, electrolyte correction, and in severe cases a kidney transplant. The effectiveness of treatment depends critically on early detection — the sooner doctors start monitoring the kidneys, the sooner they can begin supportive treatment and dialysis. There is no specific treatment proven to limit the damage.

Prevention: no orange-russet gilled mushroom with a cobwebby cortina goes into the basket. NO EXCEPTIONS. It has no culinary value, and there are no similar edible species on a dangerous scale (the chanterelle has ridges instead of gills, honey fungus has a ring and paler gills).