Tetany resulting from uncontrolled muscle spasms may indicate a malfunction of the?

Parathyroid gland.

The parathyroid glands are four small glands located on the back of the thyroid gland. They produce parathyroid hormone (PTH), which regulates calcium levels in the blood. When PTH levels are too low, calcium levels can drop, leading to tetany. Tetany is a condition characterized by uncontrolled muscle spasms.