A 61-year-old man comes to the office for follow-up of long-standing type 2 diabetes mellitus. Treatment currently consists of metformin, dietary modification, and regular exercise. On his current regimen, the patient's weight has been mostly stable over the last 2 years, but he has noticed some weight loss in the last 6 weeks. He also has mild constipation but no abdominal pain, nausea, or excessive urination. Medical history is significant for hyperlipidemia and hypertension, for which he takes atorvastatin, amlodipine, and valsartan. He also takes low-dose aspirin and a daily multivitamin. The patient does not drink alcohol but has a 45-pack-year smoking history. His father had type 2 diabetes mellitus and died of a stroke, and his mother had thyroid cancer that required surgery. Blood pressure is 134/80 mm Hg and pulse is 88/min. BMI is 30 kg/m². Neck examination is normal. Lungs are clear to auscultation. Abdominal examination reveals no masses or tenderness. Laboratory results are as follows:
Six months ago, his chemistry profile was normal.
Which of the following is the best next step in evaluation of this patient?

Question

A 61-year-old man comes to the office for follow-up of long-standing type 2 diabetes mellitus. Treatment currently consists of metformin, dietary modification, and regular exercise. On his current regimen, the patient's weight has been mostly stable over the last 2 years, but he has noticed some weight loss in the last 6 weeks. He also has mild constipation but no abdominal pain, nausea, or excessive urination. Medical history is significant for hyperlipidemia and hypertension, for which he takes atorvastatin, amlodipine, and valsartan. He also takes low-dose aspirin and a daily multivitamin. The patient does not drink alcohol but has a 45-pack-year smoking history. His father had type 2 diabetes mellitus and died of a stroke, and his mother had thyroid cancer that required surgery. Blood pressure is 134/80 mm Hg and pulse is 88/min. BMI is 30 kg/m². Neck examination is normal. Lungs are clear to auscultation. Abdominal examination reveals no masses or tenderness. Laboratory results are as follows:

Six months ago, his chemistry profile was normal.
Which of the following is the best next step in evaluation of this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c136_14d0_8f63_f7a517204b9d_MD0005_00 This patient has newly discovered hypercalcemia. Patients with mild hypercalcemia are often asymptomatic, but common initial manifestations may include constipation (as in this patient), fatigue, nausea, and nephrolithiasis. The first step in the evaluation of hypercalcemia is to repeat the serum calcium with concurrent measurement of serum parathyroid hormone (PTH) to distinguish PTH-dependent (eg, primary hyperparathyroidism) from non-PTH-dependent causes. Hypercalcemia with an elevated (or high-normal) PTH suggests excessive secretion of PTH, whereas non-PTH-dependent causes have suppressed PTH secretion (PTH <20 pg/mL). Even when malignancy is suspected, PTH remains the first step in the evaluation of hypercalcemia as the incidence of primary hyperparathyroidism is higher in patients with cancer than in the general population. Assay results are generally available within a few hours. (Choices A, C, and D) Subsequent testing in patients with non-PTH-dependent hypercalcemia may include chest x-ray (eg, for malignancy, granulomatous diseases), serum and urinary protein electrophoresis (for multiple myeloma), PTH-related protein (for humoral hypercalcemia of malignancy), and vitamin D levels (eg, for exogenous vitamin D intake, granulomatous diseases). However, PTH should be measured first to rule out hyperparathyroidism, especially in a stable outpatient. (Choice E) Urinary calcium should be measured in patients with PTH-dependent hypercalcemia to differentiate familial hypocalciuric hypercalcemia (a rare disorder due to mutations in the calcium-sensing receptor and leading to low urinary calcium excretion) from primary hyperparathyroidism (in which urinary calcium excretion is normal or elevated), but only after PTH-dependent hypercalcemia is confirmed. Educational objective: Hypercalcemia can be categorized based on the parathyroid hormone (PTH) level: PTH dependent (elevated or high-normal PTH) or non-PTH dependent (suppressed PTH). Further evaluation should be based on the initial PTH measurement. References: Hypercalcemia: an evidence-based approach to clinical cases. (http://www.ncbi.nlm.nih.gov/pubmed/19395781)

A 61-Year-Old Man Comes to the Office for Follow-Up of Long-Standing