AIM: To evaluate retrospectively the additive clinical value of combined thyroglobulin (Tg) and antithyroglobulin antibody (TgAb) measurements to define recurrent and persistent disease in patients with differentiated thyroid cancer. MATERIALS/ METHODS: 181 patients with differentiated thyroid cancer were included in the study. The nonstable disease group (recurrent and persistent disease) had 61 patients with 24-36 months follow-up period. The stable disease group (without recurrence or persistence) had 120 patients with 21-28 months follow-up period. We compared Tg and combined Tg-TgAb levels on the sixth month after the ablation between two groups. RESULTS: Optimal threshold values for Tg, TgAb measurements were calculated statistically as 4.45 ng/ml and 27.8 IU/ml. Optimal sensitivity and specificity for 4.45 ng/ml Tg levels were 52.5 and 91.7%. We also evaluated different Tg threshold values. We found sensitivity was 54.2% and specificity 86.7% for 2 ng/ml and sensitivity was 40.7% and specificity 96.7% for 10 ng/ml Tg levels. By the odds ratio (OR) rule, the obtained sensitivity and specificity were 68.3 and 90% (if Tg>10 ng/ml or TgAb>27.8 IU/ml), 78.3 and 90% (if Tg>4.45 ng/ml or TgAb>27.8 IU/ml), and 80% and 85% (if Tg>2 ng/ml or TgAb>27.8 IU/ml). Sensitivity increased with statistical significance from 52.5 to 78.3% (P<0.001) and decreased with statistical insignificance from 91.7 to 90% (P>0.05) for the optimal thresholds. CONCLUSION: Combined Tg-TgAb values were found more useful than only Tg for recurrent and persistent diseases. Combined Tg and TgAb measurements seemed to be a useful marker.
AIM: To evaluate retrospectively the additive clinical value of combined thyroglobulin (Tg) and antithyroglobulin antibody (TgAb) measurements to define recurrent and persistent disease in patients with differentiated thyroid cancer. MATERIALS/ METHODS: 181 patients with differentiated thyroid cancer were included in the study. The nonstable disease group (recurrent and persistent disease) had 61 patients with 24-36 months follow-up period. The stable disease group (without recurrence or persistence) had 120 patients with 21-28 months follow-up period. We compared Tg and combined Tg-TgAb levels on the sixth month after the ablation between two groups. RESULTS: Optimal threshold values for Tg, TgAb measurements were calculated statistically as 4.45 ng/ml and 27.8 IU/ml. Optimal sensitivity and specificity for 4.45 ng/ml Tg levels were 52.5 and 91.7%. We also evaluated different Tg threshold values. We found sensitivity was 54.2% and specificity 86.7% for 2 ng/ml and sensitivity was 40.7% and specificity 96.7% for 10 ng/ml Tg levels. By the odds ratio (OR) rule, the obtained sensitivity and specificity were 68.3 and 90% (if Tg>10 ng/ml or TgAb>27.8 IU/ml), 78.3 and 90% (if Tg>4.45 ng/ml or TgAb>27.8 IU/ml), and 80% and 85% (if Tg>2 ng/ml or TgAb>27.8 IU/ml). Sensitivity increased with statistical significance from 52.5 to 78.3% (P<0.001) and decreased with statistical insignificance from 91.7 to 90% (P>0.05) for the optimal thresholds. CONCLUSION: Combined Tg-TgAb values were found more useful than only Tg for recurrent and persistent diseases. Combined Tg and TgAb measurements seemed to be a useful marker.