A 65-year-old woman comes to the office after a screening DXA scan revealed osteoporosis. The patient has occasional back and hip pain but has had no falls or fractures. She has no significant medical history and takes no medications. Her mother has osteoporosis. The patient does not use tobacco, alcohol, or illicit drugs. She walks 1-2 miles daily and consumes a balanced diet. Vital signs are within normal limits. BMI is 23 kg/m². Physical examination reveals nonlocalized bony tenderness of the spine. The remainder of the examination shows no abnormalities. Laboratory results are as follows: Which of the following is the best next step in management of this patient?

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11ec25c8_d511_994c_bc81_bf7005c6c6e4_MD0003_00 Osteoporosis is common in postmenopausal women due to accelerated bone loss from loss of estrogen. Initial evaluation is aimed at ruling out secondary causes of bone loss, with further workup indicated in patients with significant laboratory abnormalities on initial studies (eg, complete blood count, metabolic panel including calcium, 25-hydroxyvitamin D), as in this patient. In addition, in the absence of fracture (eg, vertebral compression fracture, which could cause localized spine tenderness), nonlocalized bone pain and tenderness, as seen in this patient, are uncommon in postmenopausal osteoporosis and also suggest secondary causes of bone loss (eg, osteomalacia, malignancy). This patient has osteoporosis associated with normocytic anemia, renal insufficiency, and hypercalcemia with a suppressed parathyroid hormone level, suggestive of multiple myeloma. Her elevated protein gap (ie, serum total protein ‒ serum albumin >4 g/dL) likely reflects a monoclonal gammopathy. In addition to the classic punched-out skeletal lesions, multiple myeloma can cause rapidly progressive generalized bone loss due to increased levels of osteoclast-activating factor secreted by the neoplastic cells. The bone loss resembles that of primary osteoporosis and can lead to fragility fractures. Further evaluation for multiple myeloma includes serum protein electrophoresis and either serum free light chain analysis or urine protein electrophoresis. (Choice B) Celiac disease can cause vitamin D deficiency (due to malabsorption), leading to decreased intestinal calcium absorption and bone loss. However, serum 25-hydroxyvitamin D would be low, and PTH would be reflexively elevated. In addition, anemia is typically microcytic (iron deficiency), and renal failure and hypercalcemia are unexpected. (Choice C) Bisphosphonates are commonly used in patients with postmenopausal osteoporosis. However, renal insufficiency is a contraindication to bisphosphonate therapy, and this patient requires additional evaluation before starting definitive treatment. (Choices A and D) Parathyroid scintigraphy is obtained in preparation for surgery in patients with primary hyperparathyroidism (PHPT). A 24-hour urinary calcium is measured to assess risk of renal complications (eg, nephrolithiasis) in patients with asymptomatic PHPT (and to differentiate PHPT from familial hypocalciuric hypercalcemia, a benign condition). Although PHPT can cause diffuse bone loss, bone pain, and hypercalcemia, it would be associated with an elevated parathyroid hormone level, and renal insufficiency and anemia would be atypical. Educational objective: The evaluation of reduced bone density is aimed at ruling out secondary causes of bone loss. Bone loss associated with anemia, renal insufficiency, and hypercalcemia suggests multiple myeloma. References: Management of endocrine disease: secondary osteoporosis: pathophysiology and management. (http://www.ncbi.nlm.nih.gov/pubmed/25971649)

A 65-Year-Old Woman Comes to the Office After a Screening