⚠️ Orellanine — The Kidney‑Damaging Mushroom Toxin You Need to Know About

Summary: Orellanine is a powerful nephrotoxic mycotoxin found in certain Cortinarius mushrooms. Poisoning is marked by a long latency period and a high risk of acute and chronic kidney failure. This article explores its chemistry, occurrence, mechanism of action, clinical course, diagnosis, treatment, prognosis, prevention, and historical cases.

1. Introduction

Orellanine was first identified as the toxic compound in certain Cortinarius mushrooms found in Europe and North America. When consumed, the damage often appears days or even weeks later, making it one of the most insidious mushroom toxins.

2. Chemistry & Structure

• Orellanine is a tetrahydroxylated, di‑N‑oxidized bipyridine derivative.

• In mushrooms, it is often stored as glycosidic precursors; in the human body, the active toxin is released.

• It is structurally related to bipyridyl herbicides (such as paraquat) and promotes oxidative radical formation.

3. Which Mushrooms Contain Orellanine?

The most notorious orellanine‑containing mushrooms belong to the genus Cortinarius (webcaps):

• Fool’s Webcap — Cortinarius orellanus

• Deadly Webcap — Cortinarius rubellus

• Other toxic species within the Cortinarius “orellani group”

⚠️ Webcaps are often plain brown to orange with a fine cobweb‑like veil (cortina) on the stem. They are easily confused with edible mushrooms such as chanterelles or funnel mushrooms, which has led to fatal poisonings.

4. Mechanism of Action

• Orellanine accumulates in kidney tubules and causes selective tubular necrosis.

• Mechanisms include:

  • Inhibition of protein synthesis in kidney cells.

  • Generation of reactive oxygen species and depletion of glutathione.

  • Lipid peroxidation and long‑lasting oxidative damage.

• Orellanine can persist in kidney tissue for months.

5. Clinical Course & Symptoms

• Latency period: typically 2–14 days after ingestion (sometimes longer).

• Early phase: mild nausea, vomiting, or diarrhea may occur but often absent.

• Later phase: signs of acute kidney injury — reduced urine output, swelling, fatigue, nausea, electrolyte imbalance.

• Advanced stage: severe renal failure requiring dialysis, sometimes permanent.

6. Diagnosis

• History: mushroom consumption within the last 1–3 weeks is critical.

• Laboratory findings: elevated creatinine, urea, electrolyte disturbances.

• Special tests: orellanine can be detected in mushroom tissue, blood, or urine (HPLC‑MS), though not routinely available.

• Kidney biopsy: reveals acute tubular necrosis and interstitial changes.

7. Treatment & Management

• No specific antidote for orellanine exists.

• Early measures: gastric lavage and activated charcoal if patient presents shortly after ingestion.

• Supportive therapy: IV fluids, electrolyte correction, treatment of complications.

• Renal replacement therapy: dialysis is often required; some patients remain dialysis‑dependent or need kidney transplantation.

• Experimental approaches: antioxidants such as N‑acetylcysteine or corticosteroids have been tried, but evidence is limited.

8. Prognosis

• Depends on dose, timing of treatment, and individual susceptibility.

• Many documented cases end in chronic kidney failure; even with treatment, recovery is uncertain.

• Early supportive care may improve outcomes, but risk of permanent renal damage remains high.

9. Prevention & Foraging Advice

• Never eat webcaps. Cortinarius species are difficult to identify and pose a deadly risk.

• Avoid collecting brownish, nondescript mushrooms unless confirmed safe by an expert.

• Keep samples or photos of consumed mushrooms for identification if poisoning is suspected.

10. Historical Cases & Significance

• A mass poisoning in Poland in the 1950s led to the identification of orellanine as a nephrotoxin.

• Cases in Scandinavia, Central Europe, and North America continue to be reported, many resulting in long‑term dialysis or kidney transplants.

11. FAQ

How long before symptoms appear?Often several days to two weeks, sometimes longer.

Can cooking destroy orellanine?No. Orellanine is stable to heat and other common preparation methods.

Is there a home test?No. Only specialized labs can detect orellanine.

12. Conclusion

Orellanine is a selective, kidney‑damaging toxin found in Cortinarius mushrooms such as the Fool’s Webcap and Deadly Webcap. Its long latency, irreversible kidney damage, and lack of antidote make it one of the most dangerous mushroom toxins known. The only safe approach is prevention: never eat webcaps.

Disclaimer: This article is for educational purposes only. In suspected mushroom poisoning, seek emergency medical care immediately.