WBR0877
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| Author | [[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]] |
|---|---|
| Exam Type | USMLE Step 1 |
| Main Category | Pathophysiology |
| Sub Category | Endocrine |
| 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 | Decreased serum calcium |
| Answer A Explanation | Serum calcium is usually elevated in patients with primary hyperparathyroidism. |
| Answer B | Decreased alkaline phosphatase levels |
| Answer B Explanation | Alkaline phosphatase levels are usually elevated in patients with primary hyperparathyroidism. |
| Answer C | Increased urinary cAMP |
| Answer C Explanation | Increased urinary cAMP levels are another sign of primary hyperparathyroidism. |
| Answer D | Increased urinary cystatin C |
| Answer D Explanation | Increase in urinary cystatin C is indicative of renal injury and is used in the diagnosis of acute kidney injury. |
| Answer E | Increased urinary NGAL (neutrophil gelatinase-associated lipocalin) |
| Answer E Explanation | 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 | C |
| 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. |
| Approved | Yes |
| Keyword | Urinary cAMP, Primary hyperparathyroidism, Hyperparathyroidism, Parathyroid, Hypercalcemia |
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