Hypocalcemia that develops in hyperparathyroid patients treated with parathyroidectomy or in patients with end-stage renal disease treated with calcimimetic drugs. It is caused by a sudden decrease in serum parathyroid hormone levels, which in turn increase the uptake of calcium, magnesium, and phosphate by bone. Clinical consequences include tetany (repetitive muscle twitching) especially in patients whose calcium deficiency is severe.