WBR0794

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Renal
Prompt	[[Prompt::A 47 year old patient with HIV presents to the emergency department for 3 hours of excruciating left flank pain with minor hematuria. The emergency physician suspects a renal colic and orders a non-contrast abdominopelvic CT scan that comes back negative. Further work-up does not reveal any abnormalities despite the patient being in severe pain and not responding to analgesic therapy. The consulted urologist decides to intervene and prepares the patient for an interventional ureteroscopy. During the procedure, the surgeon recuperates 2 separate stones measuring around 1.5 cm each. If 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 kidney stones that may not be detected even on CT scan.
Answer D	AnswerD::Atorvastatin
Answer D Explanation	AnswerDExp::Atorvastatin is not associated with kidney stones.
Answer E	AnswerE::Augmentin
Answer E Explanation	AnswerEExp::Augmentin is not associated with kidney stones.
Right Answer	RightAnswer::C
Explanation	[[Explanation::Indinavir is a protease inhibitor used commonly to treat HIV. A significant portion of patients receiving this drug 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 warranted. Invasive intervention is sometimes needed in patients with severe pain, sepsis, or prolonged obstruction affecting renal function. Learning objective: Indinavir is a protease inhibitor that can lead to nephrolithiasis with radiolucent stones even on CT scan. References: Matlaga BR, Shah OD, Assimos DG. Drug-induced urinary calculi. Rev Urol. 2003;5(4):227-31. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Indinavir, WBRKeyword::Kidney stones
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::