A 56-year-old woman is found to have hypercalcemia during routine laboratory testing for a life insurance policy. She has a history of moderate asthma and has been evaluated for 2 episodes of acute bronchitis in the last 3 years. The patient has a 30-pack-year smoking history but does not use alcohol or illicit drugs. Her family history is negative for hypercalcemia. Current medications include inhaled budesonide and albuterol, and the patient takes a daily multivitamin tablet. Her temperature is 36.7 C (98 F), blood pressure is 120/70 mm Hg, pulse is 76/min, and respirations are 14/min. Neurologic examination shows no focal deficits and deep-tendon reflexes are normal. Laboratory results are as follows: Review of the patient's medical records reveals a serum calcium level of 10.9 mg/dL a year ago. Which of the following is the best next step to determine the cause of this patient's hypercalcemia?

Question

A 56-year-old woman is found to have hypercalcemia during routine laboratory testing for a life insurance policy.  She has a history of moderate asthma and has been evaluated for 2 episodes of acute bronchitis in the last 3 years.  The patient has a 30-pack-year smoking history but does not use alcohol or illicit drugs.  Her family history is negative for hypercalcemia.  Current medications include inhaled budesonide and albuterol, and the patient takes a daily multivitamin tablet.  Her temperature is 36.7 C (98 F), blood pressure is 120/70 mm Hg, pulse is 76/min, and respirations are 14/min.  Neurologic examination shows no focal deficits and deep-tendon reflexes are normal.  Laboratory results are as follows:  Review of the patient's medical records reveals a serum calcium level of 10.9 mg/dL a year ago.  Which of the following is the best next step to determine the cause of this patient's hypercalcemia?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d3b2_cd05_bc81_f146a93496bb_MD0003_00 Causes of hypercalcemia can be categorized on the basis of parathyroid hormone (PTH) levels as PTH-dependent or PTH-independent: PTH-independent hypercalcemia (suppressed PTH) is usually due to malignancy, vitamin D toxicity, or extra-renal conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D in granulomatous diseases (eg, sarcoidosis). PTH-dependent hypercalcemia (elevated or inappropriately normal PTH) is usually due to primary hyperparathyroidism (PHPT). This patient has chronic, asymptomatic hypercalcemia, most likely due to PHPT. In normal individuals, elevated plasma calcium suppresses PTH secretion. However, in PHPT, PTH secretion from autonomously functioning parathyroid adenomas or parathyroid hyperplasia is not suppressed. Most patients with PHPT present with mild, asymptomatic hypercalcemia, although potential clinical features may include nephrolithiasis, osteoporosis, nausea, constipation, and neuropsychiatric symptoms ("stones, bones, abdominal moans, psychic groans"). In this patient with chronic, asymptomatic hypercalcemia and no family history of hypercalcemia, an elevated PTH level would be virtually diagnostic for PHPT. suppresses PTH secretion (Choices A, B, E, and F) Most cases of PTH-independent hypercalcemia are due to malignancy. If the PTH is suppressed, diagnostic options may include chest imaging (primary or metastatic lung cancer), PTH-related protein (humoral hypercalcemia of malignancy), scintigraphic bone scan (bony metastasis), and serum protein electrophoresis (multiple myeloma). However, in hypercalcemia due to malignancy, serum calcium is typically much higher (often >14 mg/dL) than in this patient and more acute. In addition, patients are more likely to be symptomatic (eg, polyuria, dehydration, mental status changes). (Choice C) Although elevated alkaline phosphatase can suggest a possible bone disorder, it is not specific enough to detail the type of bone condition causing the hypercalcemia. Educational objective: Causes of hypercalcemia should be categorized on the basis of parathyroid hormone (PTH) levels. PTH-independent hypercalcemia (suppressed PTH) is usually due to malignancy. PTH-dependent hypercalcemia (elevated or inappropriately normal PTH) is usually due to primary hyperparathyroidism. References: Differential diagnosis of hypercalcemia. (http://www.ncbi.nlm.nih.gov/pubmed/1763670) Hypercalcemia and parathyroid disorders. (http://www.ncbi.nlm.nih.gov/pubmed/1599819)

A 56-Year-Old Woman Is Found to Have Hypercalcemia During Routine