Surgical removal of the parathyroid glands leads to a deficiency in parathyroid hormone (PTH), which is essential for calcium homeostasis. Without PTH, calcium levels drop, causing hypocalcemia and the clinical state known as hypoparathyroidism. This condition manifests with symptoms like muscle cramps and tetany due to low serum calcium. It is a common complication following thyroidectomy or parathyroidectomy if the glands are inadvertently removed or damaged. Therefore, preservation of the parathyroid glands during neck surgery is critical to prevent hypoparathyroidism.

Reference: Harrison's Principles of Internal Medicine, J. Larry Jameson et al., 20th Edition.