Intramuscular Injection of Mashed Parathyroid Tissue Into a Forearm During Thyroid Surgery to Prevent Permanent Postoperative Parathyroid Insufficiency (IMIPAT Study)

Parathyroid insufficiency is a common complication in thyroid surgery and occurs in 6.6 to 24%. Up to 4.4% suffer from permanent hypoparathyroidism requiring life-time substitution of calcium and vitamin D in order to maintain a normal calcium homeostasis. To prevent permanent postoperative parathyroid insufficiency after thyroidectomy, devascularized parathyroid glands are re-implanted intramuscularly by standard. To achieve graft function, meticulous preparation and division of parathyroid tissue is necessary as a prerequisite for tissue nutrition by diffusion until a recapillarization of the parathyroid fragments sets in. There are persistent controversies about the optimal technique for the autotransplantation. The injection of mashed parathyroid tissue into a muscle appears to be a fast, secure and easy tech-nique to provide a sufficient parathyroid hormone (PTH) production in cases of insufficient production of the glands left in-situ. The study is based on the hypothesis that intramuscular injection of mashed parathyroid tissue is a safe procedure that enables graft survival through diffusion and allows for the subsequent production of systemically measurable levels of parathyroid hormone (PTH). The intervention consists of injecting mashed parathyroid tissue into the brachioradialis muscle of the non-dominant arm. The primary objective is to evaluate this technique with respect to both local complications arising from the transplantation procedure and the functional performance of the graft over time. Outcome measures include the PTH gradient between the transplanted and non-transplanted arms, parathyroid hormone levels measured in the antecubital fossa of both arms, and calcium levels. The study population comprises 100 patients, and the trial is designed as a prospective multicentre study. The risk-benefit assessment indicates that the risks associated with participation-particularly local complications and potential graft malfunction-are expected to be low. In patients with familial or renal hyperparathyroidism, autotransplantation of small parathyroid fragments (approximately 1 mm in diameter) has been standard practice for decades. Additionally, the injection of mashed parathyroid tissue into the sternocleidomastoid muscle during surgery has been performed in many centers for years. However, that approach has the limitation that PTH originating from the graft cannot be reliably measured due to anatomical constraints.