Mercury Chloride (Mercuric Chloride / Corrosive Sublimate) Poisoning

Overview

Mechanism

• Corrosive mucosal injury (GI tract, mouth)
• Direct nephrotoxicity (proximal tubular necrosis)
• Cellular necrosis with acidophilic inclusions in affected cells

Acute Clinical Presentation

• Acrid metallic taste, choking sensation, hoarseness of voice
• Corrosive, hemorrhagic gastroenteritis - mouth/tongue corroded with gray-white coating, burning pain in mouth/stomach/abdomen, bloody stools
• Characteristic graying of the oral mucosa (Tintinalli's Emergency Medicine)
• Shock and cardiovascular collapse can follow rapidly
• Acute kidney injury - oliguria/anuria, hematuria, albuminuria, from both direct tubular toxicity and hypoperfusion from shock; can progress to acute tubular necrosis
• Thrombocytopenia and bone marrow depression
• If inhaled as vapor: salivation, gingivitis, loosened teeth
• If given IV: dyspnea, cyanosis, hypotension, convulsions
• Death typically from anaphylactic shock, ventricular fibrillation, or renal failure; fatal period is usually 3-5 days (P C Dikshit Textbook of Forensic Medicine and Toxicology, p. 474)

Chronic Poisoning

• Excessive salivation, swollen/painful salivary glands, foul breath
• Gum inflammation/ulceration with a brownish-blue line, loose teeth, jaw necrosis
• GI: nausea, vomiting, diarrhea, colicky pain
• Neurologic ("erethism"): irritability, emotional lability, insomnia, shyness, tremor; plus neurasthenia (fatigue, depression, poor concentration)
• Renal: proteinuria progressing to nephrotic syndrome
• Mercuria lentis - brownish reflex on the anterior lens capsule seen on slit-lamp exam in exposed workers
• Acrodynia ("pink disease") in children - immune-mediated rash, painful erythema/edema of palms/soles, sweating, irritability, hypotonia

Diagnosis

• Clinical picture plus exposure history
• 24-hour urinary mercury (after a 5-day seafood-free diet, since seafood contains organic mercury that can falsely elevate levels); normal <10-15 mcg/L, >20 mcg/L suggests meaningful exposure but levels correlate poorly with severity
• Levels are most useful for confirming exposure and tracking response to chelation, not for grading toxicity

Treatment

1. Decontamination: Gastric lavage with warm water; egg albumin, skimmed milk, or magnesium carbonate can bind mercury (forms an insoluble albuminate that limits absorption); activated charcoal with magnesium sulfate
2. Chemical antidote: Sodium formaldehyde sulfoxylate (reduces mercuric chloride to less toxic metallic mercury) - most effective if given within the first 30 minutes
3. Chelation therapy:
   • Dimercaprol (BAL) - drug of choice for acute inorganic mercury poisoning, given IM (classic forensic dosing: 3.5 mg/kg every 4 hours for 2 days, then tapering); most effective if started within 1-2 hours of ingestion. Contraindicated in organic (methylmercury) poisoning as it can worsen CNS effects.
   • Succimer (DMSA) - oral chelator, preferred for chronic or milder toxicity, fewer side effects than penicillamine
   • Penicillamine - oral alternative, 250 mg four times daily
   • DMPS - used in some countries, fewer side effects than BAL
   • EDTA has also been used and may be superior to BAL in some respects, but is contraindicated with renal damage
4. Supportive care: IV fluids/diuresis for renal support, treatment of shock, hemodialysis if acute kidney injury develops (mercury-BAL complex is dialyzable); plasma exchange transfusion has been reported beneficial in severe mercuric chloride ingestion (Tintinalli's Emergency Medicine)

Key Distinguishing Feature from Arsenic Poisoning

Hepatorenal Syndrome - Acute Kidney Injury (HRS-AKI)

Definition

Diagnostic Criteria

• Rise in serum creatinine ≥0.3 mg/dL within 48 hours, OR
• ≥50% rise in creatinine from baseline within the last 7 days (KDIGO-based ICA-AKI criteria)

1. Cirrhosis with ascites (decompensated cirrhosis)
2. AKI meeting the above criteria
3. No/only partial response to volume expansion: absent or partial response after 2 days of albumin 1 g/kg/day (max 100 g/day) with diuretic withdrawal
4. Absence of shock
5. No current or recent nephrotoxic drug exposure
6. No macroscopic signs of structural kidney injury (proteinuria >500 mg/day, microhematuria >50 RBC/hpf, or abnormal renal ultrasound)

Distinguishing HRS-AKI from ATN (useful bedside clues)

Treatment

1. First-line: Vasoconstrictor + albumin
   • Terlipressin plus albumin is the treatment of choice worldwide - a splanchnic vasoconstrictor that improves effective renal perfusion. Given by bolus or continuous IV infusion; requires monitoring for ischemic complications.
   • Norepinephrine plus albumin is used where terlipressin is unavailable (e.g., historically in the US, though terlipressin - Terlivaz - is now FDA-approved), typically requiring ICU-level monitoring.
   • Midodrine + octreotide + albumin is a third-line, less effective oral/subcutaneous alternative used when vasopressors/ICU care aren't feasible.
   • ADQI/ICA 2024 stopping rules for vasoconstrictors: serum creatinine returns within 0.3 mg/dL of baseline, clear treatment failure (persistent renal failure >48h, need for dialysis, or intractable anuria), or a maximum of 14 days of therapy.
   • AASLD (2024) and ACG (2021) guidelines recommend vasoconstrictors for KDIGO stage 2-3 AKI.
2. Renal replacement therapy (RRT/dialysis) - reserved for treatment failures, mainly as a bridge to liver transplantation; use remains somewhat controversial as standalone therapy.
3. TIPS (transjugular intrahepatic portosystemic shunt) - can be considered in select patients, though evidence quality is limited (2024 Cochrane review flagged insufficient high-quality data).
4. Liver transplantation - the only definitive/curative treatment, since it addresses the underlying portal hypertension and circulatory dysfunction; renal function typically recovers post-transplant. All eligible HRS-AKI patients should be evaluated for transplant.

Recent Evidence (2024-2025 meta-analyses, PMIDs for reference)

• Terlipressin + albumin significantly improves HRS reversal versus placebo (PMID: 40207491, 2025 meta-analysis).
• Terlipressin appears comparable to or more effective than noradrenaline for HRS-AKI reversal, though with more ischemic adverse events; noradrenaline may have a mortality-neutral profile as an alternative where terlipressin access is limited (PMID: 39295934, PMID: 38285703, PMID: 38460713, all 2024).
• A 2024 Cochrane review on TIPS for HRS found the evidence base too limited/low-quality to draw firm conclusions on benefit (PMID: 38235907).