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A 17-year-old boy presents to the emergency department after his mother found him unconscious in his car in his garage. He was last seen sitting in his car listening to music on the car radio. He regains consciousness in the emergency department and denies drug use, trauma, fever, or other infectious symptoms. His urine drug screen is negative. He says that he remembers feeling nauseated and dizzy and having a headache before he passed out. What is the most likely cause of his symptoms?

A. Influenza

B. Carbon monoxide poisoning

C. Marijuana use

D. Heroin use

E. Meningitis

Answer: B

Carbon monoxide (CO) is an odorless gas produced by incomplete combustion of carbon fuels. Common sources include house fires and automobile exhaust. Other sources include improperly ventilated water heaters, stoves, or fireplaces. One should suspect CO poisoning if a patient is found unconscious in a house fire or a running automobile. The patient in the clinical vignette likely had his car running while he was listening to music from the car radio. Mild symptoms can include malaise, nausea/vomiting, headache, dizziness, or confusion. Severe symptoms include syncope, seizures, coma, respiratory depression, and death. CO detectors are available and are often used in conjunction with smoke detectors.

Influenza and meningitis are unlikely because there are no signs of infection or fever. Recreational drug use is also less likely given the negative drug screen.

A 1-year-old child presents for a routine well visit. You perform blood lead screening, and the child's lead level is found to be 6 μg/dL. The child lives in an older home, built in the 1950s, and the parents note that there is chipping paint in the window sill in the child's room. Which statement about lead poisoning is true?

A. Lead, like other metals including iron, serves some physiologic functions in the body.

B. Lead-based paint was banned in the United States in 1940.

C. Nervous system development can be affected at blood lead levels < 5 μg/dL.

D. The most common source of lead exposure in children is imported cosmetics.

E. The child in the vignette should receive chelation therapy.

Answer: C

Lead ...

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