Calcium and phosphorus levels have an inverse relationship, with calcium being stored primarily in bones. Calcium is regulated by parathyroid hormone, calcitonin, and vitamin D. Hypercalcemia can be caused by hyperparathyroidism, malignancy, vitamin D overdose, or prolonged immobilization. Symptoms of hypercalcemia include decreased memory, confusion, fatigue, and dysrhythmias. Treatment involves hydration, loop diuretics, calcitonin, mobilization, and decreasing calcium intake. Nursing care focuses on monitoring symptoms, renal and cardiac function, electrolyte levels, and risks for injuries, constipation, and fluid and electrolyte imbalances.