A 27-year-old man presents to the emergency department with altered mental status. He has become gradually more confused over the past several days. His wife also notes he has had diarrhea, nausea and vomiting, and abdominal pain for the past week. The patient has a history of depression and multiple suicide attempts. He takes fluoxetine as well as over-the-counter pain medications for a recent muscle strain. He works in a large industrial compound that manufactures semiconductors. He exercises regularly and recently has started making his own beer at home. His temperature is 98.3°F (36.8°C), blood pressure is 107/75 mmHg, pulse is 110/min, respirations are 22/min, and oxygen saturation is 99% on room air. Physical exam reveals a confused man with a garlic odor on his breath and the finding in Figure A. Cardiopulmonary exam reveals a rapid heart rate with no murmurs and clear breath sounds. Which of the following is the most likely etiology of this patient's symptoms?
Arsenic
Cyanide
Acetaminophen
Iron
Arsenic
This patient who works in the semiconductor industry and presents with confusion, hypotension, tachycardia, a garlic odor, and Mees lines (Figure A) most likely has arsenic poisoning.

Arsenic poisoning can occur due to exposure to contaminated drinking water, industrial jobs, insecticides, and certain preservatives. Arsenic inhibits enzymes requiring lipoic acid as a cofactor; thus, it disrupts ATP production and causes oxidative stress. Signs and symptoms of arsenic poisoning include Mees lines (white horizontal/parallel lines on the nail beds), nausea, vomiting, abdominal pain, diarrhea, confusion, hypotension, tachycardia, and a garlic odor on the breath. Severe complications are more common with acute exposures and can include shock, pulmonary edema, rhabdomyolysis, and death. Findings consistent with chronic poisoning include anemia, neuropathy, ataxia, and somnolence. A urine arsenic level can support the diagnosis. The treatment of arsenic poisoning is chelating agents such as dimercaprol and supportive therapy. Dimercaprol is a nephrotoxic chelating agent with a narrow therapeutic index and should be used with care.

Moon et al. study the association between low and moderate arsenic exposure and cardiovascular disease. The authors find that even low-dose exposure to arsenic increased the risk of cardiovascular disease, coronary artery disease, and stroke mortality. The authors recommend population-level interventions to decrease exposure to arsenic.

Figure/Illustration A is the physical exam finding of Mees lines with multiple parallel white lines in the nail bed (blue arrows).

Incorrect Answers:
Answer A: Acetaminophen overdose has a spectrum of presentations, from non-specific symptoms which can include no symptoms at all to a toxic appearance with nausea, vomiting, jaundice, and altered mental status. Patients should have a 4-hour acetaminophen level drawn. If it falls above the treatment line on the Rummack Matthew nomogram, treatment with N-acetylcysteine should be started. Acetaminophen can cause fulminant liver failure and markedly elevated liver enzymes.

Answer C: Cyanide inhibits complex IV in the electron transport chain. It can present after exposure to industrial fires. Patients may present with altered mental status and a profound lactic acidosis that does not respond to oxygen administration with rapid progression to death. The treatment involves the administration of hydroxocobalamin which combines with cyanide to form the non-toxic compound cyanocobalamin.

Answer D: Iron overdose presents with nausea, vomiting, diarrhea (bloody), hemorrhagic gastritis, and lactic acidosis. A serum iron level should be ordered to aid in diagnosis. Treatment of acute overdose includes chelation therapy with deferoxamine.

Answer E: Lead poisoning can present with constipation, irritability, lethargy, lead lines on radiography, and microcytic anemia with basophilic stippling. Treatment depends on the severity and can involve removal from exposure or chelating therapy with agents such as succimer.

Bullet Summary:
Arsenic poisoning presents with Mees lines, nausea, vomiting, abdominal pain, confusion, unstable vitals, and a classic “garlic odor.”