Normal parathyroid hormone levels do not exclude permanent hypoparathyroidism after thyroidectomy.

BACKGROUND: Permanent hypoparathyroidism has become the most common and the most severe complication after thyroid surgery. In our experience, some patients suffer from permanent hypocalcemia and related symptoms despite normal parathyroid hormone (PTH) values after thyroid surgery. The aim of this work was to present a series of such patients with long-term hypocalcemia and normal PTH values to evaluate to what extent parathyroid function was impaired by thyroidectomy, and determine whether irregularities of bone and calcium metabolism were associated with this phenomenon. METHODS: We present a series of eight patients with normal PTH and subnormal calcium levels at follow-up 2 months after thyroid surgery. Outcome parameters were intra- and postoperative PTH and calcium kinetics, and the following markers of calcium and bone metabolism at long-term follow-up: serum calcium, total serum albumin, ionized calcium, magnesium, PTH, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, urinary calcium, urinary creatinine, osteocalcin, c-terminal telopeptide of type I collagen, and alkaline phosphatase. RESULTS: All patients had normal calcium and PTH levels at the start of the operation. The intraoperative decline in PTH was >90%; the trough (3.3% of preoperative value) was reached 3 hours after surgery. Patients underwent complete determination of bone metabolism parameters during long-term follow-up 13.8 ± 2.4 months after surgery. Hypocalcemia was found in all eight patients, as well as PTH levels within the normal range. In three patients (3/8 = 37.5%), none of the other parameters was altered. In the remaining five patients, only isolated abnormalities in bone and calcium metabolism parameters were found (i.e., alterations in urinary calcium, thyrotropin, 25-hydroxyvitamin D, osteocalcin, and c-terminal telopeptide of type I collagen). CONCLUSIONS: An intraoperative injury to the parathyroid glands or their vascularization is the likely contributing factor to the development of permanent hypocalcemia with normal PTH values after thyroid surgery. The remaining parathyroid tissue is subject to a maximum stimulus by hypocalcemia and, therefore, is able to maintain PTH values in the normal range. These are still too low to re-establish normal serum calcium levels. In these patients, the term "hypoparathyroidism" might be replaced with "parathyroid insufficiency."

Intra- and postoperative parathyroid hormone-kinetics do not advocate for autotransplantation of discolored parathyroid glands during thyroidectomy.

BACKGROUND: Thyroidectomy continues to pose the risk of typical complications, including postoperative hypocalcemia and permanent hypoparathyroidism. The strategic decision on how to preserve parathyroid hormone (PTH) secretion relies on assessing the viability of the parathyroid glands (PGs). The aim of this study was to assess parathyroid discoloration as an indicator for loss of parathyroid function. METHODS: The prospective study included 29 patients (24 women, 5 men; age 53.2 ± 13.0 years) who underwent near-total or total thyroidectomy. An intra- and postoperative PTH and calcium monitoring was performed. The intraoperative situs of the PGs was documented by a study protocol. The patients were grouped in three categories: group A, 12 patients with four visualized and normally colored PGs; group B, 13 patients with four visualized and three or four discolored PGs; group C, 4 patients who had undergone autotransplantation of two PGs. RESULTS: Compared to group A, groups B and C showed sharper intraoperative PTH declines. PTH values recovered more quickly in group B than in group C. However, no significant differences in PTH kinetics were found in the general linear model for repeated measures (p = 0.132). However, a significantly higher incidence of protracted hypocalcemia-related symptoms for more than 14 postoperative days was found for group C (50.0%) than for groups A (0%) and B (0%; p = 0.011). None of the patients developed permanent hypoparathyroidism. CONCLUSIONS: The function of discolored PGs is only transiently impaired and recovers within a short time after surgery. Our observations do not support autotransplantation as a generally applicable first-line intervention for discolored PGs in the absence of other criteria for autotransplantation.