WBR0877

Author	[[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathophysiology
Sub Category	SubCategory::Endocrine
Prompt	[[Prompt::A 43-year-old woman presents to the emergency department with acute onset flank pain increasing in severity over the past 2 hours. After initial evaluation, a non-contrast abdominopelvic CT scan reveals 2 small, 1 cm stones lodged at the left ureteropelvic junction. The patient expresses her frustration and explains that this is the fourth time she has been admitted to the hospital for urinary stones in the past 2 months. The complete work-up subsequently reveals a normal creatinine, normal vitamin D levels, with elevated urinary calcium and elevated serum parathyroid hormone. Which of the following additional findings can be expected in this patient?]]
Answer A	AnswerA::Decreased serum calcium
Answer A Explanation	AnswerAExp::Serum calcium is usually elevated in patients with primary hyperparathyroidism.
Answer B	AnswerB::Decreased alkaline phosphatase levels
Answer B Explanation	AnswerBExp::Alkaline phosphatase levels are usually elevated in patients with primary hyperparathyroidism.
Answer C	AnswerC::Increased urinary cAMP
Answer C Explanation	AnswerCExp::Increased urinary cAMP levels are another sign of primary hyperparathyroidism.
Answer D	AnswerD::Increased urinary cystatin C
Answer D Explanation	AnswerDExp::Increase in urinary cystatin C is indicative of renal injury and is used in the diagnosis of acute kidney injury.
Answer E	AnswerE::Increased urinary NGAL (neutrophil gelatinase-associated lipocalin)
Answer E Explanation	AnswerEExp::Increase in urinary NGAL (neutrophil gelatinase-associated lipocalin) is also indicative of renal injury and is used in the diagnosis of acute kidney injury.
Right Answer	RightAnswer::C
Explanation	[[Explanation::Primary hyperparathyroidism is the most common etiology of elevated serum calcium most often caused by a single functional adenoma excessively secreting parathyroid hormone. Clinically, most patients are asymptomatic with hypercalcemia found incidentally. Other possible presentations include recurrent nephrolithiasis, bone disease, and neuromuscular symptoms. Without proper intervention, frequent nephrolithiasis, decreased bone mineral density, and increased risk of death from cardiovascular causes ensue. Lab findings include hypercalcemia, hypercalciuria, elevated alkaline phosphatase, and elevated PTH. Another finding that can be used in the evaluation is elevated urinary cAMP. Treatment of primary hyperparathyroidism is usually surgical. Educational Objective: Urinary cAMP is elevated in patients with primary hyperparathyroidism. References: Marcocci C, Cetani F. Clinical practice. Primary hyperparathyroidism. N Engl J Med. 2011;365(25):2389-97. Broadus AE. Nephrogenous Cyclic AMP as a Parathyroid Function Test. Nephron. 1979;23(2-3):136-141.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Urinary cAMP, WBRKeyword::Primary hyperparathyroidism, WBRKeyword::Hyperparathyroidism, WBRKeyword::Parathyroid, WBRKeyword::Hypercalcemia
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Order in Linked Questions	LinkedOrder::