Parathyroid disease is a condition that affects the parathyroid glands, which are four tiny glands located near the thyroid gland in the neck. The condition is characterized by the overproduction or underproduction of parathyroid hormone (PTH), which can lead to a range of symptoms, including bone pain, kidney stones, and fatigue. Treatment for parathyroid disease often involves surgery to remove the affected gland or glands.