How is hypoparathyroidism prevented following thyroid surgery?

Updated: Jan 25, 2018
  • Author: Pramod K Sharma, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Answer

The best way to preserve parathyroid gland function is to identify the glands and to maintain their blood supply. A large cadaveric study to identify the most common positions of the parathyroid glands demonstrated that 77% of superior parathyroid glands were at the cricothyroid junction and intimately associated with the RLN. About 22% of the superior parathyroid glands were on the posterior surface of the upper lobe of the thyroid. Approximately 1% of the superior glands were behind the junction of the hypopharynx and upper esophagus.

The study demonstrated that the location of the inferior parathyroid glands was variable. Forty-two percent were on the anterior or lateral surfaces of the lower lobe of the thyroid, often hidden by vessels or creases in the thyroid. Thirty-nine percent were located within the superior tongue of the thymus. Fifteen percent were extrathyroidal and lateral to the lower lobe. Two percent were in the mediastinal thymus, and another 2% were in other ectopic positions, such as the carotid sheath. The ectopic inferior parathyroid glands were consistently associated with remnant thymus tissue.

The inferior parathyroid glands and the thymus both develop from the third branchial pouch, a finding that explains the close association of these structures. The inferior parathyroid glands receive their blood supply from the inferior thyroid artery. The superior parathyroids also usually receive their blood supply from the inferior thyroid artery. However, in some cases, the superior parathyroids receive their vascular supply from the superior thyroid artery, the anastomotic loop between the inferior and superior thyroid arteries, or direct branches off the thyroid gland.

The key to parathyroid preservation is identifying the parathyroids and preserving their blood supply by ligating all vessels distal to them. Ligate the vessels as close to the thyroid gland as possible. Recognition of the parathyroid glands, which appear in various shapes and which have a caramel-like color, is critical. When they lose their blood supply, they often darken in appearance.

The surgical wound and the excised thyroid gland should be carefully examined for parathyroid tissue. The devascularized gland (pathologically confirmed with frozen-section analysis), should be removed, cut into 1- to 2-mm pieces, and reimplanted into a pocket created in the sternocleidomastoid muscle or strap muscle. The location may be marked with a permanent suture or a metallic hemoclip for easier identification in any future surgeries.


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