WBR0714
| Author | PageAuthor::William J Gibson (Reviewed by Serge Korjian) |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Biochemistry, MainCategory::Pathology, MainCategory::Pharmacology |
| Sub Category | SubCategory::General Principles |
| Prompt | [[Prompt::A 7-year-old boy is brought to the physician by his parents for loss of appetite, abdominal pain, lethargy and constipation that has become worse over the past several weeks. The parents have received a notification that their son’s performance in school has deteriorated during this same period. On physical examination, the physician notes thin, grey-blue lines visible along the margin of the patient’s gums. The patient’s condition is most likely caused by exposure to which of the following?]] |
| Answer A | AnswerA::Arsenic |
| Answer A Explanation | AnswerAExp::Arsenic poisoning is not associated with Burton's lines. |
| Answer B | AnswerB::Manual thermometers |
| Answer B Explanation | AnswerBExp::Mercury in manual thermometers would not cause Burton's lines. |
| Answer C | AnswerC::Old paint |
| Answer C Explanation | AnswerCExp::Chronic exposure to lead in old paint can cause lead poisoning, which is characterized by reduced cognitive abilities, gastrointestinal problems, and Burton's lines. |
| Answer D | AnswerD::Pesticides |
| Answer D Explanation | AnswerDExp::Many pesticides (organophosphates) are potent neurotoxins, functioning by inhibiting the action of acetylcholinesterase (AChE) in nerve cells. They would not be responsible for Burton's lines. |
| Answer E | AnswerE::Zinc |
| Answer E Explanation | AnswerEExp::Zinc is not associated with Burton's lines. |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::Lead-contaminated household dust from old paint is the major source of lead exposure to children in the U.S. The symptoms of chronic lead poisoning include neurological problems, such as reduced cognitive abilities associated with gastrointestinal problems, such as loss of appetite, abdominal pain, vomiting, and constipation. On physical exam, Burton’s lines may be present which are thin, grey-blue lines visible along the margin of the patient’s gums. Diagnosis is usually confirmed by a blood lead level (BLL). Any BLL higher than 10 µg/dL is considered positive for lead toxicity. Another important sign of lead poisoning is hypochromic microcytic anemia and basophilic stippling of red blood cells. Although the most important part of treating lead poisoning is decreasing exposure to lead, chelation therapy may be required to reduce existing blood lead levels particularly if blood levels are greater than 45 µg/dL. such as Succimer, EDTA, or Dimercaprol (BAL). Educational Objective: Chronic exposure to lead in old paint can cause lead poisoning, which is characterized by reduced cognitive abilities, gastrointestinal problems, and Burton's lines. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Lead poisoning, WBRKeyword::Lead toxicity, WBRKeyword::Toxin, WBRKeyword::Toxic, WBRKeyword::Poison, WBRKeyword::Poisoning, WBRKeyword::Lead, WBRKeyword::Heme, WBRKeyword::Hematology, WBRKeyword::Blood, WBRKeyword::Lethargy |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |