Introduction An increase in serum calcium level Mechanisms and pathophysiology dietary causes calcium ingestion (milk-alkali syndrome) hypervitaminosis D hypervitaminosis A pharmacologic causes thiazides causes increased distal tubule reabsorption of calcium used to treat hypercalciuria malignancy-associated causes Paget's disease typically does not result in hypercalcemia can be come hypercalcemic if patient is immobilized squamous cell cancer of the lung ectopic production of PTH (PTH related peptide - PTHrP) multiple myeloma production of IL-1 activates osteoclast-driven bone resorption sarcoidosis granulomatous macrophages produce 1α-hydroxylase which produces high amounts of 1,25 vitamin D hyperparathyroid genetic causes familial hypocalciuric hypercalcemia defect in calcium sensor of parathyroid gland there is a loss of negative feedback on PTH by hypercalcemia PTH levels are normal to high despite high serum calcium levels urine excretion of calcium is low key feature distinguishing primary hyperparathyroidism from FHH other causes hyperthyroid Addison's disease Zollinger-Ellison syndrome Presentation Symptoms CNS confusion stupor weakness gastrointestinal constipation anorexia nausea vomiting kidney polyuria kidney stones polydipsia Physical exam weakness decreased/absent reflexes EKG shortened QTc interval Treatment Conservative hydration saline diuresis Pharmacologic loop diuretics bisphosphonates mithramycin calcitonin galium nitrate Other dialysis