Endocrine Abstracts

Anatomical proximity, common blood supply and variability of location of the parathyroid glands make them prone to damage in the course of thyroid gland surgery. Total thyroidectomy (TT) poses a greater risk of postsurgical hypoparathyroidism (hypoPT) than a unilateral lobectomy, and neck lymph nodes dissection is an established risk factor of HypoPT. HypoPT lasting longer than 6–12 months postoperatively is considered permanent. The mechanism responsible for the recovery of parathyroid gland function has been a subject of debate.

We present two patients in whom a neck sonography showed a hypoechogenic, vascularized structure in the bed of the thyroid gland which had been removed for papillary thyroid cancer (PTC).

A hypoechogenic lesion was visualized in the bed of the right thyroid lobe two years after TT for PTC of the ipsilateral thyroid lobe in a 70 yr man. Epithelial cells with signs of atypia, scattered lymphocytes as well as microcalcifications, suspicious for cancer recurrence, were found on fine needle biopsy. Excision of the lesion was performed. On the pathologic examination parathyroid adenoma, composed of main, oxyphyllic and clear cells was found. The patient was normocalcemic before as well as after the operation. Hypophosphatemia had been the only biochemical feature of hyperparathyroidism.

A 51-yr woman underwent TT for bifocal PTC. Parathyroid glands were not found in the pathological material, however she required treatment for postsurgical hypoPT. In the eighth year of the follow-up a raise in serum calcium concentration made further treatment for HypoPT unnecessary. Meanwhile a hypoechogenic vascularized 10 mm structure in the bed of the left thyroid lobe was shown on the sonography. Serum concentration of PTH, total calcium and phosphate were: 56 pg/ml (n 12–65 pg/ml), 2.4 mmol/l (n 2.2–2.65 mmol/l), 0.96 mmol/l (n 0.81–1.45 mmol/l), respectively. Scintigraphy with 99mTc-MIBI using planar and SPECT/CT technique was performed to elucidate a character of the lesion. A hot spot situated on the left and 15 mm beneath the thyroid cartilage, corresponding to the enlarged parathyroid gland was visualized.

According to the Guidelines for Treatment of Chronic hypoPT in Adults released recently by ESE, serum calcium concentration should be maintained in the low or slightly below normal range in order to avoid hypercalciuria.

In cases of postsurgical hypoPT, keeping low serum calcium concentration may favor hypertrophy or hyperplasia of the remaining functioning parathyroid parenchyma, which especially in patients with neck cancer anamnesis needs to be differentiated form a malignancy.