Predictive Value of Serum Thyroglobulin After Surgery for Thyroid Carcinoma

Objective To determine the relationship between stimulated serum thyroglobulin levels (taken 3 months after total thyroidectomy) and tumor stage and recurrence in patients with well‐differentiated thyroid carcinoma. Study Design Retrospective chart review in a tertiary care institution. Methods Two hundred thirteen consecutive patients with well differentiated thyroid carcinoma treated between 1983 and 1998 were identified. Data were collected on clinicopathological variables, stimulated serum thyroglobulin levels obtained 3 months after total thyroidectomy prior to 131 I therapy and recurrence. Results A high postoperative thyroglobulin level was significantly associated with advanced‐stage disease at presentation ( P = .005, Kruskall‐Wallis) but not with any of the other clinicopathological variables. Patients with a thyroglobulin level greater than 20 pmol/L had a significantly increased risk of disease recurrence on univariate analysis (n = 213 [ P = .0001, log rank test]), and in the Cox proportional‐hazards model, both advanced tumor stage ( P = .001, relative hazard, 3.4 [95% confidence interval [CI]: 2.4–4.9]) and a thyroglobulin level greater than 20 pmol/L ( P = .001, relative hazard, 5.1 [95% CI: 2.0–13.1]) were significant predictors of recurrence. No other variables significantly altered the hazards model. Conclusions Advanced tumor stage at diagnosis and a stimulated thyroglobulin level greater than 20 pmol/L taken 3 months after total thyroidectomy were independent predictors of disease recurrence. Patients with a thyroglobulin level greater than 20 pmol/L are at increased risk of recurrence and may be candidates for more intensive follow‐up or additional treatment.