PTH and Hypercalcemia: Parathyroid crisis is a rare and serious complication of primary hyperparathyroidism and is characterized by extremely high circulating levels of parathyroid hormone and acute onset of severe hypercalcemia (calcium > 3.5 mmol/L or 14 mg/dL) with associated symptoms of multiple organ failure, such as metabolic encephalopathy, renal insufficiency, gastrointestinal symptoms, and cardiac arrhythmia [11].