Soru

Zorluk: OrtaOccupational and Environmental Exposures

A 38-year-old previously healthy man is rushed to the emergency department due to the acute onset of severe, diffuse abdominal pain, intractable vomiting, and voluminous watery diarrhea. He also complains of a painful, burning sensation in his hands and feet. His spouse notes that he started a new job two weeks ago at an industrial plant that manufactures pressure-treated lumber and specialized agricultural compounds. On physical examination, his blood pressure is 90/55 mmHg, and his pulse is 115/min. He appears profoundly dehydrated, and a distinct garlic-like odor is noted on his breath. An electrocardiogram is obtained and demonstrates a prolonged QTc interval. Which of the following cellular targets is most likely directly inhibited by the primary toxin responsible for this patient's presentation?

  1. Pyruvate dehydrogenaseCevap
  2. B
    Acetylcholinesterase
  3. C
    Cytochrome c oxidase
  4. D
    Ferrochelatase
  5. E
    Na+/K+Na^+/K^+-ATPase

Cevap

Pyruvate dehydrogenase
The patient's presentation of severe secretory diarrhea ('rice-water' stools), intractable vomiting, garlic-scented breath, QTc prolongation, and a painful sensorimotor neuropathy in the context of exposure to wood preservatives and agricultural chemicals is classic for acute arsenic poisoning. Arsenic exerts its toxic effects primarily by binding to sulfhydryl groups, most notably on lipoic acid. Lipoic acid is an essential cofactor for the pyruvate dehydrogenase complex, which is responsible for converting pyruvate to acetyl-CoA. Inhibition of this enzyme complex halts the Krebs cycle, leading to severe depletion of cellular ATP, lactic acidosis, and subsequent systemic toxicity.

Adım Adım Çözüm

1
Identify the toxidrome based on the clinical presentation and occupational history.
The combination of severe gastrointestinal distress ('rice-water' diarrhea), peripheral neuropathy, garlic-scented breath, and QTc prolongation in a wood preservative worker points to acute arsenic poisoning.
Recognizing the specific clinical signature of environmental toxins is required to establish the diagnosis.
2
Determine the biochemical mechanism of the identified toxin.
Arsenic exerts its toxic effects by binding to lipoic acid, which is a crucial cofactor for the pyruvate dehydrogenase complex.
Identifying the directly inhibited cellular target answers the specific question asked in the stem.

Anahtar Kavram

Pathophysiology and clinical presentation of acute arsenic toxicity.
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