1 Endocrinology Unit I, Department of Clinical and Experimental Medicine, University Hospital of Pisa , Italy .
2 Unit of Internal Medicine and Endocrinology, Fondazione Salvatore Maugeri, University of Pavia , Pavia, Italy .
Thyroid. 2018 Mar;28(3):288-294. doi: 10.1089/thy.2017.0052.
In order to establish whether thyroglobulin autoantibodies (TgAb) influence the metabolic clearance of thyroglobulin (Tg) in humans, serum Tg and TgAb were correlated shortly after radioiodine (I) treatment.
Samples were collected from 30 consecutive patients undergoing I activity for Graves' hyperthyroidism at the time of treatment and every 15 days thereafter, up to 90 days. Tg and TgAb were measured by immunometric assays (functional sensitivities: 0.1 ng/mL and 8 IU/mL).
Tg was detectable in all patients at day 0. Tg concentrations rose from a mean of 33.2 ng/mL [confidence interval (CI) 17.8-61.0 ng/mL] at day 0 to a mean of 214.6 ng/mL [CI 116.9-393.4 ng/mL] at day 30 and then steadily decreased, reaching the lowest concentration at day 90 (M = 10.9 ng/mL [CI 5.5-20.9 ng/mL]). Compared to their levels at day 0 (M = 23.6 IU/mL [CI 10.5-52.9 IU/mL]), TgAb remained stable through day 15 and then gradually increased up to a mean of 116.6 IU/mL [CI 51.9-262.2 IU/mL] at day 90. Patients were then split into two groups according to their TgAb status at day 0: undetectable (<8 IU/mL; 9 patients) or detectable (≥8 IU/mL; 21 patients) TgAb. Compared to the other cohort, patients with detectable TgAb showed significantly lower Tg concentrations at day 0 (M = 20.3 ng/mL [CI 10.1-40.2 ng/mL] vs. M = 101.8 ng/mL [CI 36.6-279.8 ng/mL]), similar at day 15, lower levels at day 30 (M = 146.5 ng/mL [CI 74.3-287.8 ng/mL] vs. M = 514.8 ng/mL [CI 187.8-1407.9 ng/mL]), at day 45 (M = 87.5 ng/mL [CI 43.1-176.6 ng/mL] vs. M = 337.9 ng/mL [CI 120.1-947.0 ng/mL]), at day 60 (M = 61.6 ng/mL [CI 31.0-121.4 ng/mL] vs. M = 255.8 ng/mL [CI 79.0-823.8 ng/mL]), and at day 75 (M = 24.5 ng/mL [CI 11.9-49.2 ng/mL] vs. M = 249.5 ng/mL [CI 63.5-971.1 ng/mL]), and similar levels at day 90. Patients with detectable TgAb showed a lower (M = 182.5 ng/mL [CI 92.0-361.0 ng/mL] vs. M = 514.8 ng/mL [CI 187.8-1407.9 ng/mL]) and an earlier (day 15 vs. day 30) peak of Tg. The mean Tg concentration was lower in patients with detectable TgAb than in those with undetectable TgAb (area under the curve: 17,340 ± 16,481 ng/mL vs. 36,883 ± 44,625 ng/mL; p = 0.02).
TgAb influence the changes in Tg concentrations observed immediately after I treatment, inducing lower levels and an earlier peak of Tg. These observations indicate that TgAb significantly influence the metabolic clearance of Tg, supporting the concept that their interference in the measurement of Tg is mainly due to an in vivo effect.
为了确定甲状腺球蛋白自身抗体 (TgAb) 是否会影响人类甲状腺球蛋白 (Tg) 的代谢清除率，我们在碘（I）治疗后不久就将血清 Tg 和 TgAb 进行了相关分析。
从 30 例因格雷夫斯病（Graves' hyperthyroidism）而接受 I 治疗的连续患者中采集样本，在治疗当天以及之后的每 15 天采集一次，最多采集 90 天。通过免疫计量测定法（功能灵敏度：0.1ng/mL 和 8IU/mL）来测量 Tg 和 TgAb。
所有患者在第 0 天均能检测到 Tg。Tg 浓度从第 0 天的平均 33.2ng/mL（17.8-61.0ng/mL）上升到第 30 天的平均 214.6ng/mL（116.9-393.4ng/mL），然后稳定下降，第 90 天达到最低浓度 10.9ng/mL（5.5-20.9ng/mL）。与第 0 天的水平相比（M=23.6IU/mL（10.5-52.9IU/mL）），TgAb 在第 15 天保持稳定，然后逐渐升高，第 90 天达到平均 116.6IU/mL（51.9-262.2IU/mL）。根据第 0 天的 TgAb 状态，将患者分为两组：未检出（<8IU/mL；9 例）或检出（≥8IU/mL；21 例）TgAb。与另一组相比，检出 TgAb 的患者在第 0 天的 Tg 浓度明显较低（M=20.3ng/mL（10.1-40.2ng/mL）），在第 15 天相似，在第 30 天（M=146.5ng/mL（74.3-287.8ng/mL）），第 45 天（M=87.5ng/mL（43.1-176.6ng/mL）），第 60 天（M=61.6ng/mL（31.0-121.4ng/mL）），第 75 天（M=24.5ng/mL（11.9-49.2ng/mL）），与第 90 天相似。检出 TgAb 的患者 Tg 的峰值较低（M=182.5ng/mL（92.0-361.0ng/mL））且出现较早（第 15 天比第 30 天）。与未检出 TgAb 的患者相比，检出 TgAb 的患者的 Tg 平均浓度较低（曲线下面积：17340±16481ng/mL 与 36883±44625ng/mL；p=0.02）。
TgAb 影响 I 治疗后立即观察到的 Tg 浓度变化，导致 Tg 水平较低和峰值较早。这些观察结果表明，TgAb 显著影响 Tg 的代谢清除率，支持 TgAb 对 Tg 测量的干扰主要是由于体内作用的概念。
