Endocrine Abstracts

Objectives: Any condition involving increased follicular cell mass may raise serum thyroglobulin levels. However, we occasionally encounter patients with markedly elevated preoperative thyroglobulin levels, indicating thyroid cancer with substantial metastatic burden. We aimed to investigate the clinical significance of markedly elevated preoperative serum thyroglobulin levels.

Methods: From 2019 to 2021, we analyzed patients underwent thyroid surgery for papillary thyroid cancer (PTC) or benign, with a focus on preoperative thyroglobulin levels ≥500ng/ml.

Results: In 7,737 PTC cases and 781 benign cases, 84 in each group had preoperative thyroglobulin levels ≥500ng/ml. Forty (48%) had the BRAF V600E mutation, and 11 (13%) had the TERT promoter mutation in PTC. In the 24 cases with a cancer size >4 cm, 3 (13%) showed distant metastasis, and 1 (4%) had another nodule >2 cm; none had diffuse thyroid disease (DTD). In the 32 cases with a cancer size >2 cm but ≤4 cm, 4 (13%) showed distant metastasis. 4 (12%) had another nodule >2 cm, and 3 (9%) exhibited DTD; two had both conditions. In the 28 cases with a cancer size ≤2 cm, 1 (4%) showed distant metastasis. 15 (53%) had another nodule >2 cm, and 9 (32%) exhibited DTD; two had both conditions. In benign, for 50 cases with size >4 cm, multinodular, 1 (2%) exhibited DTD; for 12 cases with size >2 cm but ≤4 cm, 3 (25%) cases showed DTD; and for 22 cases with size ≤2 cm, no focal lesion, 22 (100%) cases exhibited DTD. Even with preoperative thyroglobulin ≥1000ng/ml, a similar pattern persisted.

Conclusions: In cases with markedly elevated preoperative thyroglobulin levels, a high cancer burden is often observed. However, it can also occur in cases with large benign nodules or DTD. Therefore, additional research is needed to determine the clinical utility when excluding such cases.