WBR0414

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Renal
Prompt	[[Prompt::A 76 year old male patient who has recently been diagnosed with heart failure presents to the physician’s office complaining of dyspnea at rest and fatigue. Physical examination reveals jugular venous distension and bilateral lower extremity pitting edema. Pulmonary auscultation reveals crackles at the base of lungs bilaterally. The physician prescribes a diuretic to relieve his symptoms. Several weeks later, the patient’s routine work-up reveals elevated serum calcium and uric acid levels. Based on the image below, the diuretic prescribed to this patient acts at the level of which segment of the nephron? ]]
Answer A	AnswerA::A
Answer A Explanation	AnswerAExp::The proximal tubule is the site of action of osmotic diuretics, like mannitol, and carbonic anhydrase inhibitors, like acetazolamide.
Answer B	AnswerB::B
Answer B Explanation	AnswerBExp::Thin descending loop of Henle is not the site of action of any diuretic.
Answer C	AnswerC::C
Answer C Explanation	AnswerCExp::Thick ascending loop of Henle is the site of action of loop diuretics.
Answer D	AnswerD::D
Answer D Explanation	AnswerDExp::Thiazide diuretics inhibit NaCl reabsorption at the level of the distal tubule. Side effects of thiazide diuretics include hypercalcemia and hyperuricemia.
Answer E	AnswerE::E
Answer E Explanation	AnswerEExp::The collecting duct is the main site of action of aldosterone receptor antagonists, like spironolactone.
Right Answer	RightAnswer::D
Explanation	[[Explanation::Thiazide diuretics inhibit NaCl reabsorption at the level of the distal tubule. Thiazides are commonly prescribed for patients with heart failure. Common side effects include hyperGLUC: hyperGlycemia, hyperLipidemia, hyperUricemia, and hyperCalcemia. Educational Objective: Thiazide diuretics inhibit NaCl reabsorption by inhibiting the NaCl channel in the distal tubule. They are commonly prescribed for patients with heart failure. Common side effects include hyperGLUC: hyperGlycemia, hyperLipidemia, hyperUricemia, and hyperCalcemia. Educational Objective: References: ]]
Approved	Approved::No
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