A 51-year-old woman comes to the physician because of a persistent dry cough after an upper respiratory infection 2 months ago. She denies hemoptysis, chest pain, or weight loss. She is an ex-smoker with a 25 pack-year smoking history.
Her blood pressure is 130/72 mm Hg and her pulse is 74/min. Her BMI is 24 kg/m². Lungs are clear to auscultation. The abdomen is soft and non-tender. The remainder of the physical examination is within normal limits.
Laboratory results are as follows:

Chest x-ray reveals hilar adenopathy and a 2.0 cm left lower lung nodule.
Which of the following is the most likely cause of this patient's hypercalcemia?

Question

A 51-year-old woman comes to the physician because of a persistent dry cough after an upper respiratory infection 2 months ago. She denies hemoptysis, chest pain, or weight loss. She is an ex-smoker with a 25 pack-year smoking history.
Her blood pressure is 130/72 mm Hg and her pulse is 74/min. Her BMI is 24 kg/m². Lungs are clear to auscultation. The abdomen is soft and non-tender. The remainder of the physical examination is within normal limits.
Laboratory results are as follows:

Chest x-ray reveals hilar adenopathy and a 2.0 cm left lower lung nodule.
Which of the following is the most likely cause of this patient's hypercalcemia?

Quizplus · Accepted Answer

11ec193a_97b8_a251_853d_494ce2c0febe_MD0002_00 The first step in evaluation of confirmed hypercalcemia is to measure the PTH level. Patients with elevated PTH should then have their urinary calcium excretion measured. Primary and tertiary hyperparathyroidism present with elevated urinary calcium, while familial hypocalciuric hypercalcemia has low urinary calcium. Patients with suppressed PTH should have measurement of PTH-related peptide (PTHrP) and both 1,25-hydroxy vitamin D and 25-hydroxy vitamin D. Elevated PTHrP usually indicates solid tumor malignancy, while elevated 25-hydroxy vitamin D indicates vitamin D toxicity. This patient has elevated 1,25-hydroxy vitamin D, which is usually seen in granulomatous diseases and lymphoma. Sarcoidosis is a multisystem granulomatous disease with noncaseating tissue granulomas. Activated pulmonary macrophages produce calcitriol, which is responsible for the hypercalcemia and hypercalciuria. (Choice A) Parathyroid adenoma usually presents with elevated or high-normal PTH out of proportion to the hypercalcemia. However, this patient's low-normal PTH makes this unlikely. (Choice C) Squamous cell carcinoma is associated with elevated PTHrP causing hypercalcemia. However, it does not usually cause elevated 1,25-hydroxy vitamin D. (Choice D) Thyrotoxicosis can also result in hypercalcemia but does not usually cause elevated 1,25-hydroxy vitamin D. (Choice E) Vitamin D intoxication increases calcium and bone resorption causing hypercalcemia, but usually occurs at 25-hydroxy vitamin D levels > 150 ng/mL. Vitamin D intoxication does not cause elevated 1,25-hydroxy vitamin D. Given this patient's hilar adenopathy, sarcoidosis or lymphoma is more likely. Educational objective: Patients with hypercalcemia and elevated 1,25-hydroxy vitamin D require a chest x-ray to evaluate for granulomatous diseases (sarcoidosis) and lymphoma. __________ References: The diagnosis and management of hypercalcemia (http://www.ncbi.nlm.nih.gov/pubmed/12625112) Sarcoidosis initially manifesting as symptomatic hypercalcemia with the absence of organic involvement (http://www.ncbi.nlm.nih.gov/pubmed/12135177)

A 51-Year-Old Woman Comes to the Physician Because of a Persistent