Ectopic and extranumerary parathyroid glands location in patients with hyperparathyroidism secondary to end stage renal disease

Abstract

Supranumerary or ectopic parathyroid glands are the main cause of persistent hyperparathyroidism (HPT) in patients with end stage renal disease (ESRD) submitted to parathyroidectomy (PTx). PURPOSE: To evaluate the prevalence and location of parathyroid glands in these patients. METHODS: Thirty-five patients with ESRD and severe secondary hyperparathyroidism (HPT2) had been submitted to total PTx at HUCFF from December 2001 to July 2005. Surgery was always performed by the same surgeon, who described in details the location of the glands. RESULTS: Sixteen patients (45.7%) had ectopic glands, which were also extranumerary in five of them (14.3%). The most common locations were the thyroid parenchyma (33.3%), thyroid-thymus conduit (18.5%), and thymus (14.8%). Before PTx, the sensibility of ultrasonography and scintigraphy with technetium-99m Sestamibi was low (48.3% and 35.3%, respectively). Moreover, 51.4% of the nodules found at US were thyroid nodules. However, 99mTc-Sestamibi was useful to identify ectopic glands in those two patients with persistent HPT after PTx. CONCLUSION: The presence of extranumerary and ectopic parathyroid glands in HPT2 is sufficiently important to justify their exhaustive search. As the preoperative image exams present low sensibility to locate them, it is necessary to develop an exploratory routine embracing the most common sites of location.

An Update on the Structure of the Parathyroid Gland

“…Usually there are four parathyroid glands and each one is about the size of a split pea, weighing 30 to 40 mg, but this can be range from 2 to 6 glands, with some authors reporting up to 12 glands [12,13]. Supernumerary parathyroid glands are found in healthy individuals, most commonly with a 5th gland located in the cervical thymus [7,12,14]. The combined weight of all parathyroid glands is 120 mg in adult men and 142 mg in adult women.…”

Parathyroid Glands

“…Previous studies have reported a total of four glands in 78.6-97.5% of cases (Gilmour 1938;Akerström et al 1984;Gomes et al 2007;Hojaij et al 2011). Different percentages of cases with fewer than four glands are described in the literature.…”

Parathyroid Embryology, Anatomy, and Pathophysiology of Primary Hyperparathyroidism

“…Supernumerary glands were found in 13% of the cases, most commonly in the thymus. In the literature, the incidence of supernumerary glands is anywhere between 3% and 13% [6] [12]. Only in three percent of the cases less than four parathyroid glands are identified [6].…”