MEDizzy - Mr. Wassim is a 45-year-old man with metastatic

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Cardinal Manifestations and Presentation of Diseases 2

Mr. Wassim is a 45-year-old man with metastatic non–small-cell lung cancer undergoing chemotherapy. He presents to the hospital after his family noted that he was confused. Serum calcium is 11.5 mg/dL with a serum albumin of 2.5 g/dL. Vital signs are as follows: heart rate 132 bpm, blood pressure 90/55 mmHg, respiratory rate 18 breaths/min, temperature 37.2°C. What is the frst appropriate therapeutic response for his hypercalcemia?

ExplanationWhen serum albumin concentrations are reduced, a corrected calcium concentration is calculated by adding 0.2 mM (0.8 mg/dL) to the total calcium level for every decrement in serum albumin of 1.0 g/dL below the reference value of 4.1 g/dL for albumin and, conversely, for elevations in serum albumin. For this patient, the corrected serum calcium is elevated at 12.7 (11.5 + [4 – 2.5] × 0.8). Signifcant symptomatic hypercalcemia usually requires therapeutic intervention independent of the etiology of hypercalcemia. Initial therapy of signifcant hypercalcemia begins with volume expansion because hypercalcemia invariably leads to dehydration; 4–6 L of intravenous saline may be required over the frst 24 hours, keeping in mind that underlying comorbidities (e.g., congestive heart failure) may require the use of loop diuretics to enhance sodium and calcium excretion. However, loop diuretics should not be initiated until the volume status has been restored to normal. If there is increased calcium mobilization from bone (as in malignancy or severe hyperparathyroidism), drugs that inhibit bone resorption should be considered. Zoledronic acid (e.g., 4 mg intravenously over ~30 minutes), pamidronate (e.g., 60–90 mg intravenously over 2–4 hours), and ibandronate (2 mg intravenously over 2 hours) are bisphosphonates that are commonly used for the treatment of hypercalcemia of malignancy in adults. In patients with 1,25(OH)2D- mediated hypercalcemia, glucocorticoids are the preferred therapy, as they decrease 1,25(OH)2D production. Intravenous hydrocortisone (100–300 mg daily) or oral prednisone (40–60 mg daily) for 3–7 days is used most often.