This document discusses hypercalcemia and hypocalcemia. It covers the roles and homeostasis of calcium, along with the causes, clinical features, and management of hypercalcemia and hypocalcemia. For hypercalcemia, the main causes discussed are primary hyperparathyroidism, malignancy, vitamin D excess, and renal failure. Symptoms involve the bones, muscles, kidneys, gastrointestinal and cardiovascular systems. Diagnostic tests include serum electrolytes, PTH, and imaging. Treatment focuses on increasing urinary excretion, inhibiting bone resorption, and decreasing intestinal absorption. For hypocalcemia, chronic and acute causes are outlined. Symptoms include weakness, tingling, spasms and seizures