A total thyroidectomy involves the removal of the entire thyroid gland, primarily to treat conditions like thyroid cancer, large goiters, or hyperthyroidism. Because the four small parathyroid glands are typically located directly on the back surface of the thyroid, their close physical relationship often leads to confusion about whether they are removed. A total thyroidectomy does not intentionally include the parathyroid glands; the surgeon’s aim is always to preserve them and their function.
Distinct Roles of Thyroid and Parathyroid Glands
The thyroid and parathyroid glands are neighbors in the neck, but they serve two distinct purposes in the endocrine system. The thyroid gland produces the hormones thyroxine (T4) and triiodothyronine (T3), which regulate the body’s metabolic rate, energy use, and temperature. These hormones affect virtually every organ system, necessitating lifelong thyroid hormone replacement therapy after removal.
The parathyroid glands, usually four in number, maintain calcium homeostasis—the stable balance of calcium levels in the blood and bones. They produce parathyroid hormone (PTH) in response to low blood calcium levels. PTH acts on the bones to release calcium, on the kidneys to retain calcium, and helps activate Vitamin D to increase intestinal calcium absorption. Maintaining this balance is essential for proper nerve and muscle function, requiring preservation during thyroid surgery.
Surgical Techniques for Parathyroid Preservation
Preserving the parathyroid glands and their blood supply is one of the most technically challenging aspects of a total thyroidectomy. The typical procedure involves capsular dissection, where the surgeon carefully separates the thyroid tissue from its capsule, leaving the parathyroid glands and their blood vessels intact. The anatomical location of the glands can be highly variable, making identification a critical first step.
Surgeons use magnification loupes (special glasses providing two-and-a-half times magnification) to precisely identify the glands, which are normally about the size of a grain of rice or a small pea. The parathyroid blood supply, often arising from the inferior thyroid artery, must be protected during the ligation of the thyroid’s own blood vessels. New techniques, such as near-infrared autofluorescence (NIRAF), are used by some surgeons to confirm the location and viability of the parathyroid glands in real-time.
Parathyroid Autotransplantation
If a parathyroid gland is accidentally removed or its blood supply is compromised, the surgeon performs parathyroid autotransplantation. This involves mincing the tissue and implanting it into an accessible muscle, such as the sternocleidomastoid muscle or the forearm muscle. This procedure allows the implanted cells to re-establish a blood supply and begin producing PTH, which helps prevent permanent loss of function. While in situ preservation is ideal, autotransplantation is a necessary rescue technique.
Addressing Hypoparathyroidism After Surgery
Despite surgical efforts, damage to the parathyroid glands or their blood supply can lead to temporary or permanent hypoparathyroidism. This complication results in insufficient PTH secretion, causing hypocalcemia (an abnormally low level of calcium in the blood). Symptoms of hypocalcemia include tingling or numbness, particularly around the lips, fingers, and toes, and may progress to muscle cramps or spasms (tetany).
Immediate post-operative care involves monitoring serum calcium levels and sometimes checking the PTH level within the first 24 hours. A low PTH level in the immediate post-operative period can predict which patients are at risk for symptomatic hypocalcemia. Standard immediate treatment involves supplementation with oral calcium and an active form of Vitamin D, often calcitriol, to maximize the body’s absorption of the supplemental calcium.
In the majority of cases, hypoparathyroidism is temporary, with the glands recovering function within a few weeks or months as swelling subsides. Permanent hypoparathyroidism, defined as the need for continued calcium or active Vitamin D supplementation one year after surgery, is rare, occurring in less than 5% of adult patients treated by experienced surgeons. Patients with permanent loss of function require lifelong monitoring and management to maintain safe calcium levels.