WBR0794

Author	[[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Renal
Prompt	[[Prompt::A 47-year-old man with HIV presents to the emergency department for 3 hours of excruciating left flank pain and hematuria. The emergency physician suspects a renal colic and orders a non-contrast abdominopelvic CT scan that reveals left ureter dilation and edema without any visible obstruction. Further work-up is unremarkable. Given the patient's worsening status, the urologist decides to prepare the patient for interventional ureteroscopy. During the procedure, the surgeon recuperates 2 separate stones measuring around 1.5 cm each. Assuming the patient's condition had been caused by a medication, which of the following would be a likely culprit?]]
Answer A	AnswerA::Ibuprofen
Answer A Explanation	AnswerAExp::Ibuprofen is not associated with kidney stones.
Answer B	AnswerB::Metoprolol
Answer B Explanation	AnswerBExp::Metoprolol is not associated with kidney stones.
Answer C	AnswerC::Indinavir
Answer C Explanation	AnswerCExp::Indinavir is a protease inhibitor that can cause radiolucent kidney stones that are difficult to detect even on CT scan.
Answer D	AnswerD::Atorvastatin
Answer D Explanation	AnswerDExp::Atorvastatin is not associated with kidney stones.
Answer E	AnswerE::Raltegravir
Answer E Explanation	AnswerEExp::Raltegravir is not associated with kidney stones.
Right Answer	RightAnswer::C
Explanation	[[Explanation::Indinavir is a protease inhibitor commonly used to treat HIV. A significant portion of patients receiving this drug (4-5%) develop indinavir nephrolithiasis. Usually, indinavir stones cannot be detected on abdominal x-ray nor on abdominopelvic CT especially if the stones are purely composed of indinavir. Some patients can have mixed stones with some calcium content that may be visible. Therapy with indinavir usually needs to be discontinued permanently with a switch to another protease inhibitor. Invasive intervention is sometimes needed in patients with severe pain, sepsis, or prolonged obstruction affecting renal function. Educational Objective: Indinavir is a protease inhibitor that can lead to nephrolithiasis with radiolucent stones that may be hard to visualize on abdominal CT scan. References: Matlaga BR, Shah OD, Assimos DG. Drug-induced urinary calculi. Rev Urol. 2003;5(4):227-31.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Indinavir, WBRKeyword::Kidney stones, WBRKeyword::Radiolucent, WBRKeyword::AIDS, WBRKeyword::Protease inhibitor
Linked Question	Linked::
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