Mercury in Retrograde: The Tale of Toxicity

Introduction: Mercuric chloride is a highly toxic inorganic compound with historical medical use but severe potential for harm when ingested. Acute mercury poisoning is rare but can lead to multiorgan toxicity, particularly affecting the kidneys and gastrointestinal tract. Prompt recognition and intervention are essential to prevent long-term sequelae and mortality. Case Presentation: An 18-year-old male with a psychiatric history presented one hour after intentional ingestion of five mercuric chloride tablets. He exhibited mild abdominal symptoms, and initial laboratory studies revealed proteinuria, glycosuria, and rising creatinine. Imaging showed echogenic kidneys, and serum mercury levels were markedly elevated at 840 μg/L. He was treated with oral dimercaptosuccinic acid (DMSA), intravenous fluids, and gastrointestinal decontamination. Despite therapy, his renal function declined, with creatinine peaking at 9.6 mg/dL, requiring hemodialysis. Renal biopsy demonstrated acute tubular necrosis without immune complex deposition. After six sessions of hemodialysis and 16 days of chelation therapy, renal function and mercury levels improved, allowing discharge to psychiatric care. Discussion: Mercuric chloride exerts its nephrotoxic effects primarily through oxidative injury to proximal tubular cells, resulting in acute tubular necrosis. While chronic mercury exposure is more often associated with glomerular diseases, acute ingestion more typically causes tubular injury. Chelation with DMSA facilitates mercury elimination but may be insufficient when renal impairment occurs. In such cases, hemodialysis becomes essential for toxin clearance and metabolic support. This case underscores the importance of early, combined therapeutic interventions. Conclusion: Acute mercuric chloride ingestion is a medical emergency that can cause life-threatening renal toxicity. Timely initiation of chelation therapy and supportive measures, including hemodialysis, are crucial for recovery. This case demonstrates that even in severe presentations, multidisciplinary management can result in favorable outcomes.