Copper sulfate toxicity

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Background

  • Copper sulfate (CuSO₄) toxicity is a rare but potentially lethal poisoning caused by ingestion of copper sulfate, a powerful oxidizing agent that causes corrosive gastrointestinal injury and multiorgan failure through intravascular hemolysis, methemoglobinemia, hepatotoxicity, and acute kidney injury.[1]
  • Copper sulfate pentahydrate (CuSO₄·5H₂O) is a bright blue crystal commonly known as "blue vitriol" or "blue stone"
  • Used as a pesticide, fungicide, algaecide (pool/pond treatment), leather tanning agent, and in photography and glue manufacturing[2]
  • Also burned in Hindu and Buddhist religious ceremonies as a "good luck charm"
  • The attractive blue color makes it a risk for accidental pediatric ingestion
  • Most cases of intentional ingestion are reported from the Indian subcontinent, though cases occur worldwide[3]
  • In adults, ingestion is most commonly intentional (self-harm)
  • Toxic dose: symptoms manifest with ingestion of >1 g in adults[1]
  • Lethal dose: 10-20 g, though individual variation exists[1]
  • Mortality rate: 14-36% in severe poisoning if not treated promptly[4]
  • Early deaths result from hypovolemic shock; late deaths from hepatic failure, renal failure, or sepsis

Mechanism of toxicity

  • Copper is a powerful oxidizing agent
  • Local effect: direct corrosive injury to GI mucosa
  • Systemic effects (following absorption):
    • Oxidizes hemoglobin Fe²⁺ to Fe³⁺ → methemoglobinemia
    • Oxidative damage to red blood cell membranes → intravascular hemolysis
    • Majority of absorbed copper deposited in the liver via portal circulation → hepatocellular necrosis
    • Free hemoglobin and direct copper nephrotoxicity → acute tubular necrosis
    • Direct toxic injury to skeletal muscle → rhabdomyolysis

Clinical features

  • Characteristic blue-green vomitus and metallic taste are classic early findings[2]
  • Presentation evolves over hours to days in a predictable organ-system pattern

Early (hours)

  • Nausea, vomiting (may be blue/green colored), diarrhea (may be bloody)
  • Burning epigastric and abdominal pain
  • Hematemesis, melena (from erosive gastropathy)
  • Metallic taste
  • Excessive salivation

Intermediate (12-24 hours)

  • "Saturation gap": pulse oximetry SpO₂ reads low (e.g. 85%) while ABG PaO₂ and calculated SaO₂ are normal — classic clue for methemoglobinemia[1]
  • Chocolate-brown cyanosis that does not improve with supplemental oxygen
  • Jaundice (from hemolysis and hepatic injury)
  • Cola-colored or dark urine (hemoglobinuria)
  • Oliguria/anuria
  • Tachycardia, hypotension

Late (24-72+ hours)

Differential diagnosis

Methemoglobinemia (other causes)

  • Dapsone toxicity
  • Nitrite/nitrate exposure
  • Aniline dye exposure
  • Benzocaine toxicity
  • Amyl nitrite (poppers)

Intravascular hemolysis (other causes)

Other poisonings with similar multiorgan presentation


Microangiopathic Hemolytic Anemia (MAHA)

Evaluation

Workup

  • CBC with peripheral smear — anemia, schistocytes, spherocytes (evidence of intravascular hemolysis)
  • BMP, hepatic function panel — renal function, LFTs (AST, ALT often markedly elevated)
  • Coagulation studies (PT/INR, fibrinogen) — for DIC screening
  • LDH, haptoglobin, reticulocyte count, indirect bilirubin — hemolysis markers
  • Methemoglobin level (co-oximetry on ABG) — essential; suspect when SpO₂ on pulse oximetry is discrepant from ABG-calculated saturation
  • CK and myoglobin — for rhabdomyolysis
  • Serum amylase/lipase — pancreatitis has been reported[1]
  • Urinalysis — hemoglobinuria (dark/cola-colored urine, positive dipstick for blood without RBCs on microscopy), myoglobinuria
  • Serum copper levels:
    • Whole blood copper correlates better with severity than serum copper[6]
    • Serum copper and ceruloplasmin do not reliably correlate with clinical severity or prognosis[7]
    • Useful if etiology unknown; not essential if history is clear
  • Type and screen — anticipate need for transfusion
  • ECG — monitor for dysrhythmias
  • ABG — metabolic acidosis, methemoglobin level
  • Salicylate, acetaminophen, ethanol levels if intentional ingestion suspected
  • Peak AST >234 U/L and ALT >55 U/L have been linked with higher mortality[7]

Diagnosis

  • Primarily clinical: history of ingestion of blue crystals/solution + blue-green vomitus + erosive GI symptoms
  • Saturation gap (pulse oximetry SpO₂ << ABG SaO₂) is a key diagnostic clue for methemoglobinemia
  • Blue discoloration of vomitus, stool, or gastric contents is highly suggestive
  • Confirmed by elevated whole blood or serum copper levels, though treatment should not await results

Management

Initial resuscitation

  • Airway, breathing, circulation; continuous cardiac monitoring
  • Large-bore IV access; aggressive IV fluid resuscitation
  • Correct hypovolemic shock from GI losses and third-spacing

Reduction of absorption

  • Gastric lavage — may be considered if presenting early (within 1-2 hours), though vomiting typically occurs spontaneously; copper sulfate itself is a potent emetic[2]
  • Activated charcoal — limited data; may have some benefit if given early, but efficacy for copper is uncertain[8]
  • Dilution with milk or water — may reduce absorption if given very early
  • Do NOT induce emesis — re-exposure to corrosive agent risks further mucosal injury

Chelation therapy

  • D-Penicillamine — most commonly used chelator[1][4]
    • Dose: 1-1.5 g/day in 2-4 divided doses (oral)
    • Promotes urinary copper excretion
    • Efficacy in acute poisoning is unproven but widely recommended for severe cases
    • Nephrotoxic; use with caution or avoid if AKI develops without dialysis support
    • Contraindicated if severe corrosive GI injury prevents oral intake
  • Dimercaprol (BAL) — IM alternative when oral penicillamine is not tolerated or contraindicated[1]
    • Dose: 3-5 mg/kg/dose IM q4h for first 2 days, then taper over 7-11 days
    • Less effective than penicillamine
  • DMPS (2,3-dimercapto-1-propanesulfonate) — alternative chelator, reported effective in severe cases[5]
  • Edetate calcium disodium (CaNa₂EDTA) — another option; some recommend as first-line when penicillamine is unsafe; carries risk of acute tubular necrosis[1]
  • Trientine — second-line chelator (used primarily in Wilson disease)[4]
  • Duration of chelation is not established by evidence; generally continued until clinical improvement and copper levels normalize

Methemoglobinemia

  • Methylene blue 1-2 mg/kg IV over 5 minutes[1]
    • May repeat once after 1 hour if cyanosis persists
    • Requires intact RBCs and adequate NADPH to function — may be ineffective if severe hemolysis is present[8]
    • Contraindicated in G6PD deficiency (will worsen hemolysis)
  • If methylene blue fails:
    • Exchange transfusion — replaces hemolyzed RBCs and removes copper-laden cells; case reports of successful use[9]
    • Hyperbaric oxygen — alternative for refractory methemoglobinemia
    • Ascorbic acid — weaker reducing agent; adjunct only

Hemolysis and anemia

  • Transfuse packed red blood cells as needed
  • Monitor hemoglobin frequently (may drop rapidly)
  • Maintain high urine output (target >1 mL/kg/hr) to prevent hemoglobin cast nephropathy

Acute kidney injury

  • Aggressive IV fluid resuscitation to maintain urine output
  • Hemodialysis is ineffective at removing copper (protein-bound) but essential for supportive management of AKI and its complications (hyperkalemia, uremia, volume overload)[1]
    • Chelated copper complexes may be removed by dialysis
    • Peritoneal dialysis is inferior to hemodialysis for this purpose
  • Plasmapheresis/exchange transfusion — case reports suggest benefit in removing circulating copper and hemolyzed cells[10]

Hepatic injury

  • Supportive care; monitor LFTs and coagulation parameters serially
  • Correct coagulopathy with vitamin K, FFP as needed
  • Liver transplant may be required in fulminant hepatic failure (rare)

GI injury

  • NPO if severe erosive gastropathy
  • PPI (IV omeprazole/pantoprazole infusion)
  • Sucralfate for mucosal protection
  • Transfuse for significant GI hemorrhage

Disposition

  • All patients with confirmed or suspected significant copper sulfate ingestion (>1 g) should be admitted
  • Severe poisoning: ICU admission with continuous monitoring
    • Monitor serial CBC, renal function, LFTs, LDH, CK, methemoglobin, coagulation studies at minimum q6-12 hours for the first 48-72 hours
  • Mild/accidental ingestion with minimal symptoms:
    • Observe for at least 24 hours for delayed hemolysis, hepatic and renal injury
    • Check serial labs before considering discharge
  • All intentional ingestions: psychiatric evaluation mandatory prior to discharge
  • Complications may evolve over 3-5 days — patients may appear stable initially before rapid deterioration from hemolysis, AKI, or hepatic failure[8]
  • Prognosis is poorer with delayed presentation, large ingested volume, renal failure, and markedly elevated transaminases (AST >234 U/L)[7]
  • Contact Poison control for all cases

Medication Dosing

Dimercaprol 3-5mg/kg/dose IM q4hr x 2 days, then taper over 7-11 days IM Penicillamine 1-1.5g/day PO in 2-4 divided doses PO

See Also

External Links

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 Gamakaranage CS, Rodrigo C, Weerasinghe S, et al. Complications and management of acute copper sulphate poisoning; a case discussion. J Occup Med Toxicol. 2011;6:34. doi:10.1186/1745-6673-6-34
  2. ↑ 2.0 2.1 2.2 Saravu K, Jose J, Bhat MN, Jimmy B, Shastry BA. Acute ingestion of copper sulphate: a review on its clinical manifestations and management. Indian J Crit Care Med. 2007;11(2):74-80.
  3. ↑ Naha K, Saravu K, Shastry BA. Blue vitriol poisoning: a 10-year experience in a tertiary care hospital. Clin Toxicol. 2012;50(3):197-201.
  4. ↑ 4.0 4.1 4.2 Copper Toxicity. StatPearls. 2023. PMID: 32491602
  5. ↑ 5.0 5.1 Sinkovic A, Strdin A, Svensek F. Severe acute copper sulphate poisoning: a case report. Arh Hig Rada Toksikol. 2008;59(1):31-35. doi:10.2478/10004-1254-59-2008-1847
  6. ↑ Chuttani HK, Gupta PS, Gulati S, Gupta DN. Acute copper sulfate poisoning. Am J Med. 1965;39(5):849-854.
  7. ↑ 7.0 7.1 7.2 Acute Copper Sulfate Poisoning. Consultant360. 2016.
  8. ↑ 8.0 8.1 8.2 Bhat P, et al. A fatal and deceiving case of copper sulphate poisoning. J Anaesthesiol Clin Pharmacol. 2018;34(3):417-419. doi:10.4103/joacp.JOACP_8_17
  9. ↑ Copper Sulphate Poisoning and Exchange Transfusion. Saudi J Kidney Dis Transpl. 2011;22(6):1227-1230.
  10. ↑ Alain M, et al. She Has The Blues: An Unusual Case of Copper Sulphate Intoxication. Cureus. 2020;12(2):e7045. doi:10.7759/cureus.7045
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