It lowers calcium by 1 to 2 mg/dL, and effects last for approximately 48 hours. Calcitonin works by inhibiting bone resorption and increasing urinary calcium excretion. Bisphosphonates are also indicated in this patient. Bisphosphonates work by inhibiting bone resorption via interference with osteoclast recruitment and function. The onset is 24 to 72 hours, and the duration of effect is 2 to 4 weeks; a dose may be repeated as early as day 5. Zoledronic acid or pamidronate are FDA-approved bisphosphonates indicated for the treatment of hypercalcemia of malignancy.
In summary, this patient has severe hypercalcemia of malignancy secondary to NSCLC. Management includes hydration and treatment with calcitonin and a bisphosphonate. Because the patient has renal impairment, zoledronic acid would be recommended based on the fact that it has specific dosing for renal impairment. In addition to the above management, discontinuation of the thiazide diuretic would be indicated, as thiazide diuretics increase calcium and add another antihypertensive.
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