Parathyroids are four, small, oval, yellowish brown glands arranged in two pairs. The superior parathyroids develop with the thyroid gland from fourth branchial arch. The inferior parathyroids develop with thymus from third branchial arch. Parathyroids are endocrine glands but their secretion is not dependent on pituitary gland. The parathyroid cells are called chief cells that produce parathormone (PTH). The overall effect of PTH is to raise plasma calcium levels. Hypoparathyroidism is usually due to parathyroid gland damage occurring during thyroidectomy. Due to decreased PTH, there is hypocalcemia leading to tetany. In tetany, there is hyperexcitability of peripheral nerves. Hyperparathyroidism occurs due to increased secretion of PTH leading to hypercalcemia and its clinical manifestations. Hypercalcemia occurs when normal homeostatic mechanism is disturbed.