LAUSR

BACKGROUND Purpose To determine whether thyroid stimulating hormone level ≥30 mU/l is necessary for radioiodine (131I) remnant ablation (RRA) in patients with differentiated thyroid cancer (DTC), as well as its influencing factors and predictors. METHODS 487 DTC patients were retrospectively enrolled in this study. They were divided into two groups (TSH <30 and ≥30 mU/l) and further divided into eight subgroups (0-<30, 30-<40, 40-<50, 50-<60, 60-<70, 70-<80, 80-<90, 90-<100 mU/l). The simultaneous serum lipids level, successful rate of RRA and its influencing factors in different groups were analyzed. The receiver operating characteristic curves derived from pre-ablative thyroglobulin (pre-Tg) and pre-Tg/TSH ratio were compared for RRA success prediction performance. RESULTS There was no statistical difference in success rates of RRA between the two groups (p=0.247) and eight subgroups (p=0.685). Levels of total cholesterol (p<0.001), triglyceride (p=0.006), high-density lipoprotein cholesterol (p=0.024), low-density lipoprotein cholesterol (p=0.001), apolipoprotein B (p<0.001) and apolipoprotein E (p=0.002) were significantly higher while apoA/apoB ratio (p=0.024) were significantly lower at TSH ≥30 mU/l group. Pre-Tg level, gender and N stage were influencing factors for RRA. The area under the curve of pre-Tg level and pre-Tg/TSH ratio were 0.7611 (p<0.0001), 0.7340 (p<0.0001) for all enrolled patients and 0.7310 (p=0.0145), 0.6524 (p=0.1068) for TSH <30 mU/l respectively. CONCLUSION TSH ≥30 mU/l may not be necessary for the success of RRA. Patients with higher serum TSH level prior RRA will suffer from severer hyperlipidemia. Pre-Tg level could be used as a predictor for the success of RRA, especially when TSH <30 mU/l.