Endocrine Abstracts

JOINT1456

Perioperative PTH (pOPTH) has been proposed as a predictor of postoperative hypoparathyroidism in TT. ATA Surgical Affairs Committee 2018 estimated that PTH >15pg/mL 20 min after thyroidectomy obviates the need for calcium supplementation, while others prefer day postoperative measurement. We evaluate the dynamics of pOPTH and its relationship to preoperative and intraoperative findings in a large series of patients over fourteen years. Excluding patients with concomitant primary hyperparathyroidism, we retrospectively evaluated PTH concentrations preoperatively (prePTH), immediately postoperatively (immPTH), and the day after surgery (24hPTH). We evaluated the PTH trend and its relation to clinical characteristics, extent of surgery, autoimmunity, intraoperatively identified parathyroid glands, and thyroid weight. A total of 638 thyroidectomies were included between 2010 and 2024, 145 with central neck dissection (CND) and 132 males. Mean(SD) prePTH, immPTH, and 24hPTH were 52.1(22.6), 23.7(26.8), and 25.2(19.9) pg/mL, respectively. Globally, 24hPTH was 1.21(0.73) times higher than immediate, but 236 patients (37%) had 24hPTH lower than immPTH. This trend of increasing PTH levels did not differ between males and females, patients older than 50 years or younger (61.6% vs. 65.1%; P = 0.40), cases with and without autoimmunity (63.3% vs. 62.2%; P = 0.85), preoperative thyroid hyperfunction (58.5% vs. 64.4%; P = 0.45), or patients with 0-2 identified glands vs. 3-4 identified glands (60.1% vs. 62.9%; P = 0.55). Patients undergoing surgery for radiological, biopsy or cytological suspicion were more likely to have 24hPTH>immPTH than those undergoing surgery for clinical reasons (68.8% vs. 57.1%; P = 0.002). This trend was also significantly higher in patients who received CND (73.8% vs. 59.8%; P= 0.002) than in those who received TT alone. Out of 283 cases with immPTH<15 pg/ml, 152 (53.7%) had a higher 24hPTH, 76 of them (24.4%) >15 pg/ml. Thus, 207 patients (32.4%) had both below 15 pg/ml. Of the 229 patients with 24hPTH<15, only 22 of them (9.6%) had immPTH>15 pg/ml. Patients with decreasing PTH (24h PTH<immPTH) had higher prePTH [median(IR): 49(29) vs. 46(20) pg/ml; P= 0.003] and heavier glands at surgery [median(IR): 35.4(54.5) vs. 29.0(37.6) g; P = 0.009]. [PTH] showed a general trend towards an increase at 24 hours after surgery in relation to immediate measurement, particularly in cases with CND and those operated on for suspicion of malignancy, but there are cases with inverse dynamics, particularly in those with higher basal PTH and heavier glands at surgery. An immPTH may not be helpful in predicting low PTH, as a quarter of them recover PTH above 15 pg/ml at 24h.