低剂量电离辐射对医务放射工作人员甲状腺影响Meta分析

目的 评估低剂量电离辐射对医务放射工作人员甲状腺的影响。方法 检索1996—2022年发表的相关文献,按照纳入和排除标准筛选文献,最终纳入27篇文献,涉及22 937人。采用Stata 16.0开展Meta分析,分析血清中三碘甲状原氨酸（T₃）、游离三碘甲状腺原氨酸（FT₃）、甲状腺激素（T₄）、游离四碘甲状腺原氨酸（FT₄）、促甲状腺激素（TSH）水平和甲状腺结节检出率,并开展不同职业分类放射工作人员甲状腺功能的亚组分析。结果 采用随机效应模型分析,放射工作人员T₃、T₄水平的标准化均数差（SMD）分别为-0.19（-0.37,-0.01）和-0.34（-0.38,-0.30）,与对照组比有降低的危险性（Z=2.07、-16.06,P<0.05）;放射工作人员FT₄水平的SMD为0.22（0.06,0.39）,与对照组比有升高的危险性（Z=2.61,P<0.05）;放射工作人员甲状腺结节发生相对危险度为1.47（1.19,1.82）,与对照组比有升高的危险性（Z=3.58,P<0.05）。亚组分析结果表明介入放射学工作人员T₃、T₄、TSH水平的SMD分比为-0.29（-0.51,-0.07）、-0.31（-0.47,-0.15）、-0.43（-0.73,-0.13）（Z=-2.55、-3.86、-2.82,P<0.05）,核医学工作人员T₄水平SMD为-0.26（-0.45,-0.07）,与对照组比有降低的危险性（Z=-2.70,P<0.05）。结论 长期低剂量电离辐射可能影响放射工作人员甲状腺素水平和甲状腺结节,尤其是介入放射学工作人员,应重点关注其放射防护。     

Early prediction of hypotheroidism following 131I treatment for Graves' disease

The aim of this study was twofold. Firstly to assess the post treatment predictive value of various biochemical and immunological tests for early hypothyroidism after ¹³¹I therapy for Graves' disease, and secondly to determine whether or not pretreatment with Carbimazole protects against post treatment hypothyroidism. The early changes observed in serum T₃, T₄, TSH, thyroid microsomal and thyroglobulin antibody levels were found to be of no predictive value. A sharp rise, around 2 months, in TRAb levels following ¹³¹I therapy indicated that hypothyroidism was likely to occur. This rise was thought to reflect a greater degree of thyroid damage. Lower levels of thyroglobulin in patients who had become hypothyroid by 12 months after treatment would support this view. Five weeks Carbimazole pretreatment in this relatively small group of patients did not appear to protect against hypothyroidism.     

Value of the free triiodothyronine index in the diagnosis of hyperthyroidism

Normalized T₄ (T₄N), total T₃, T₃ resin sponge uptake (T₃U) and the response of TSH to TRH were determined in 264 patients sent for diagnosis of thyroid function. Many of these patients were diagnostic problem cases. Those with disease or medication known to invalidate the TRH test, but not those with abnormal thyroid hormone binding capacity in serum, were excluded. A free T₃ index (FT₃ index) was calculated as the product of total T₃ and T₃U.The FT₃ index tended to decline with increasing age, the mean value being significantly higher in the youngest patients (12–20-years-old) than in the older age groups. In the diagnosis of hyperthyroidism, the FT₃ index was superior not only to T₄N but also to total T₃, particularly in the presence of elevated hormone binding capacity (relatively low T₃U). It is anticipated that the FT₃ index will be most useful as a routine test for hyperthyroidism, especially in several (though not all) instances where the TRH test is invalidated.     

Scintigraphy with 201Tl for detection of thyroid cancer metastases

In four patients with disseminated papillary or follicular thyroid carcinoma metastatic sites could be demonstrated by scintigraphy with ²⁰¹Tl. Uptake was present during TSH suppression with thyroid hormone administration. In three of the four cases ²⁰¹Tl scanning revealed metastases while ¹³¹I uptake after triiodothyronine with-drawal was absent. In one patient ²⁰¹Tl demonstrated some metastatic sites while both ¹³¹I uptake and thyroglobulin levels wer negative. Uptake of ²⁰¹Tl in these metastases is at least partially, unrelated to the TSH and thyroglobulin levels or to the ¹³¹I-accumulating capacity. Scintigraphy using ²⁰¹Tl might be helpful for the detection of metastatic thyroid carcinoma in those cases where ¹³¹I uptake is absent.     

Preparation of patients with thyroid cancer for 131I scintigraphy or therapy by 1-3 weeks of thyroxine discontinuation.

To assess whether the patient preparation procedure for (131)I scintigraphy could be streamlined, we evaluated the time course of thyroid-stimulating hormone (TSH) elevation after total thyroidectomy or after discontinuation of thyroxine (T(4)) in patients with thyroid cancer. METHODS: The clinical records of 284 patients with well-differentiated thyroid cancer were reviewed. All patients had undergone total thyroidectomy. Two groups of patients were evaluated. The immediate postoperative group consisted of 176 patients who were not given thyroid hormone replacement after surgery because of planned postoperative (131)I therapy. The surveillance group consisted of 108 patients in whom T(4) replacement was stopped (without triiodothyronine [T(3)] replacement) in preparation for surveillance whole-body (131)I scintigraphy. We recorded the first TSH measurement and number of days after surgery or without thyroid hormone for each patient. RESULTS: In the immediate postoperative group, TSH levels obtained 6-65 d (median, 17 d) after surgery ranged from 18.2 to 194.8 micro IU/mL (median, 46.6 micro IU/mL). The TSH values exceeded 30 micro IU/mL in 89% of patients evaluated at 1-2 wk, in 88% of those evaluated at 2-3 wk, and in 90% of those evaluated after 3 wk. In patients discontinuing T(4) (without T(3) replacement), TSH levels obtained from 6 to 35 d (median, 20 d) later ranged from 23.4 to 214.5 micro IU/mL (median, 61.1 micro IU/mL). The TSH levels exceeded 30 micro IU/mL in 100% of patients evaluated at 1-2 wk, in 89% of those evaluated at 2-3 wk, and in 96% of those evaluated after 3 wk. CONCLUSION: In most patients with thyroid cancer being prepared for (131)I imaging or therapy, a TSH level exceeding 30 micro IU/mL can be achieved by withdrawal of thyroid hormone therapy for 1-3 wk.     

In vivo isotope study of the thyroid with 99mTcO 4 − in neonatal congenital hypothyroidism

Seventeen patients, screened from a neonatal programme for hypothyroidism were studied. As well as the scintigraphic investigations, serum TSH, T₃, free T₃, T₄, free T₄, and TBG were measured in all patients. Not more than 11.1 MBq (300 Ci) ^99mTcO ₄ ^- was administered IV. A gamma camera with a parallel-hole collimator on line with the computer was used. The method allowed good statistics to be obtained in 5–10 min in a wide field of exploration, thus reducing the problems of positioning and prolonged immobilization of the young patient. The data collected in the computer were elaborated to define better the characteristics of the thyroid image. This kind of in vivo study introduced into a screening programme, enables an anatomic diagnosis of the defect to be obtained before starting the therapy. This is undoubtedly valuable from the epidemiological point of view, enables early determination of the degree of thyroid insufficiency, and contributes to the formulation of a prognosis based on the degree and on the moment in which prenatal harm occurred.     

颅脑损伤垂体前叶激素及甲状腺激素的动态变化

目的：测定颅脑损伤后垂体和甲状腺功能，探讨其与脑伤程度的关系。方法：对２４例开颅手术的颅脑损伤患者的血清卵泡刺激素（ＦＳＨ）、黄体生成激素（ＬＨ）、促甲状腺激素（ＴＳＨ）、三碘甲状腺原氨酸（Ｔ３）、甲状腺素（Ｔ４）、生长激素（ＧＨ）、催乳素（ＰＲＬ）在伤后１０天内作了动态观察。结果：手术前，脑损伤越重，ＦＳＨ、ＬＨ、ＴＳＨ、ＧＨ、ＰＲＬ水平与对照组比较升高越明显（Ｐ＜０．０１，０．０１，０．０１，０．０５，０．０５），而且激素水平越高，预后越差，Ｔ３水平与对照组比较明显下降（Ｐ＜０．０５），Ｔ４水平无明显变化；手术后动态观察，ＦＳＨ、ＬＨ、ＧＨ、ＰＲＬ水平与手术前比较有不同程度下降，ＴＳＨ、Ｔ３、Ｔ４水平与术前比较变化不明显；ＧＨ、ＬＨ、ＰＲＬ水平下降幅度和程度越大，ＴＳＨ水平持续升高，则预后越差。结论：脑损伤后垂体和甲状腺功能有明显变化，变化程度与颅脑损伤的严重程度有关。此项测定有助于判断脑伤程度和估计预后，并为临床治疗提供依据。     

No evidence of chromosome damage in children and adolescents with differentiated thyroid carcinoma after receiving 131I radiometabolic therapy, as evaluated by micronucleus assay and microarray analysis

Purpose  As ¹³¹I therapy, used to achieve ablation of thyroid gland remnant, can cause chromosome damage in cultured peripheral lymphocytes especially, we investigated whether administration of radioiodine may induce early genome damage in peripheral T lymphocytes of adolescents with differentiated thyroid carcinoma (DTC). Methods  We studied 11 patients, aged 14.8 ± 3.1 years, who assumed ¹³¹I (range: 1.11–4.44 GBq) to ablate thyroid remnant. A blood sample for micronucleus assay and for evaluating expression of some genes involved in the DNA repair or the apoptosis pathways was obtained from each patient 1 h before (T₀) and 24 (T₁) and 48 h (T₂) post-radioiodine administration. Results  Compared to T₀, we did not find any difference in the number of micronucleated cells at both T₁ and T₂ in any subject. Nine out of 11 patients had altered expression levels in a majority of the DNA repair and apoptosis genes at T₁, which decreased at T₂. Conclusions  We demonstrated for the first time that peripheral cells of DTC children and adolescents who received ¹³¹I at a mean dosage of 3.50 ± 0.37 GBq did not show chromosome damage within 48 h from the end of radiometabolic therapy. This may be due to a prompt activation of the cell machinery that maintains the integrity of the genome to prevent harmful double-strand breaks from progressing to chromosome mutations, either by repairing the lesions or by eliminating the most seriously damaged cells via apoptosis. Statement on financial support. The present study did not receive any extramural financial assistance. It was supported exclusively by the Azienda Ospedaliero-Universitaria Pisana.     

低剂量电离辐射对放射工作人员甲状腺功能影响的Meta分析

目的 系统评估低剂量电离辐射对我国放射工作人员甲状腺功能的影响。方法 检索自1996—2017年来国内外正式刊物上发表的有关文献,严格按照预先设定的纳入和排除标准筛选文献,最终纳入15篇,共计6 332人。分析放射工作人员甲状腺功能中血清三碘甲状腺原氨酸（T3）、甲状腺素（T4）和促甲状腺素（TSH）水平。 用Stata 14.0软件进行Meta分析。结果 随机效应模型分析结果显示,放射工作人员T3水平的标准化均数差（SMD）为-0.32[95% CI（-0.61,-0.04）,P=0.03],与对照组相比有降低的危险性;单个协变量Meta回归对异质性来源进行分析仅显示性别组成与研究间异质性有关,调整研究后方差的解释比率（adjusted R-squared, Adj R²）为29.99% （P=0.03）。T4水平的SMD为-0.49[95% CI（-0.94,-0.03）,P=0.04],与对照组相比有降低的危险性;单个协变量Meta回归对异质性来源进行分析仅显示性别组成与研究间异质性有关：Adj R²为26.60%（P=0.02）。TSH水平的SMD为1.10[95% CI（0.32,1.89）,P=0.006],与对照组相比有升高的危险性。结论 长期暴露在低剂量电离辐射环境中可能对放射工作人员甲状腺功能造成不良影响,应该进一步加强对放射工作人员甲状腺的辐射防护。     

131I治疗分化型甲状腺癌术后患者疗效影响因素研究

目的 探讨影响分化型甲状腺癌（DTC）患者术后首次131I清除残留甲状腺组织（简称清甲）疗效和多次131I治疗转移灶（清灶）疗效的因素。方法回顾性分析首次接受大剂量清甲治疗的患者46例（分为成功组与未成功组）资料、多次清灶治疗的患者40例（分为临床缓解组和未缓解组）资料,对数据进行t检验、t’检验、X^2检验或Fisher确切概率法筛选影响因素,并做Logistic回归分析。结果用单因素分析筛选出手术方式、残余甲状腺质量、促甲状腺激素（TSH）水平、手术至清甲治疗时间和存在转移灶是影响清甲效果的因素（X2=5．804、t’=-5．258、t=7．376、X^2=8．867、X2=8．615,P均〈0．05）。Logistic回归分析得到的清甲成功的拟合方程为Y=3．766—0．947x,（残余甲状腺质量）-3．149x：（淋巴结转移）-3．373x,（远处转移）。对临床缓解率行单因素分析显示：甲状腺乳头状癌显著高于甲状腺滤泡状癌,仅有淋巴转移灶显著高于有远处转移灶,甲状腺全切显著高于其他手术方式（Fisher确切概率法,X。=7．278,P〈0．05）;首次131I治疗前,临床缓解组的TSH水平明显高于未缓解组,甲状腺球蛋白（Tg）水平明显低于未缓解组（t=4．489、t=-4．906,P均〈0．01）。Logistic回归分析得到清灶成功拟合方程为：Y=-0．363＋0．065x4（TSH水平）-0．250x5（Tg水平）。结论DTC患者首次清甲疗效的影响因素有手术方式、残余甲状腺质量、TSH、手术至清甲治疗时间和有无转移灶;其中残留甲状腺组织少、无淋巴结转移和无远处转移是提高成功率的关键因素。DTC患者清灶疗效的影响因素包括病理类型、手术方式、转移灶的部位、TSH和Tg;其中首次131I治疗前有较高水平的TSH和较低水平的强是提搞缓解率的关键因素。     

Cost-effective initial assessment strategies for thyroid nodules in iodine-adequate areas

Objective

In the initial assessment of thyroid nodules, thyrotropin (TSH) has very low sensitivity for assessing functional thyroid nodules (FTNs). The false negativity in FTNs and the false positivity in non-FTNs misinterpreted by TSH will raise unnecessary assessment costs. Therefore, the aim of this study is to explore the values of the TSH and color flow Doppler sonography (CFDS) combined strategies in reducing the unnecessary assessment costs.

Methods

2383 patients with thyroid nodules were retrospectively analyzed, including 107 FTNs and 2276 non-FTNs. Four strategies including TSH, CFDS, Combination 1 (TSH+/CFDS+, TSH+/CFDS?, and TSH?/CFDS+ defined as positive; TSH?/CFDS? defined as negative) and Combination 2 (TSH+/CFDS+ defined as positive; TSH+/CFDS?, TSH?/CFDS+, and TSH?/CFDS? defined as negative) were separately used for initial assessment. The four strategies were compared using the testing cost ratio of fine-needle aspiration (FNA) to thyroid scintigraphy (TS) (marked as C_FNA/TS) as main outcome measure.

Results

Compared with TSH, Combination 1 prevented 15.89 % of FTNs from unnecessary FNA, but increased the number of non-FTNs subjected to unnecessary ^99mTc-TS by 9.31 %. Combination 2 prevented 5.32 % of non-FTNs from unnecessary TS, but increased the number of FTNs subjected to unnecessary FNA by 18.69 %. When C_FNA/TS was <6.05, the lowest total cost was found in Combination 2. The TSH and Combination 1 were optimal at 6.05 ≤ C_FNA/TS ≤ 12.47 and C_FNA/TS > 12.47, respectively.

Conclusions

The combined strategies can be used to supplement TSH in the initial assessment of thyroid nodules in iodine-adequate areas, depending on the testing costs of FNA and TS.

     

Early kinetics of the human thyroid trap estimated with 99mTc and 131I

Kinetic parameters of ^99mTc and ¹³¹I thyroid trapping were compared in 13 patients (30 dynamic studies). The data were analyzed with a six-compartment model including three compartments for extrathyroid spaces. There was a good correlation between the estimates of the total iodide and pertechnetate pools (V₄+V₅). As expected, the ₁₄ loss rate constant for technetium was always higher than that for iodide.In five euthyroid patients, the unidirectional clearances (R₄₁) with TcO₄ ^– and I^– were generally of the same magnitude. The effect of TSH stimulation appears to be identical for both isotopes: an increase of R₄₁ and the total iodide and pertechnetate pool (V₄+V₅), a decrease of the isotope loss rate constant (₁₄).In two untreated thyrotoxic patients, the unidirectional clearance of ^99mTc was 2.5 times higher than that estimated with ¹³¹I. Under administration of antithyroid drug, unidirectional TcO₄ ^– clearance was lower than that of iodide in the six patients studied.A similar and greater discrepancy between early ¹³¹I and ^99mTc kinetics was observed in a patient with congenital goiter. The technetium thyroid trap was only slightly elevated, whereas unidirectional iodide clearance and (V₄+V₅) were clearly increased.This series of patients suggests that whereas there is a good correlation between early ¹³¹I and ^99mTc kinetics in euthyroid subjects, a discrepancy exists in patients with spontaneous or acquired dyshormonogenesis. This is confirmed by the segmentary study of a patient with a nodule appearing hot on the ^99mTc scintigram and cold on the ¹³¹I scan.Research supported by INSERM (CRL 7750943 B)     

Value of the first serum thyroglobulin level after total thyroidectomy for the diagnosis of metastases from differentiated thyroid carcinoma

The aim of this study was to evaluate the diagnostic significance of the first serum thyroglobulin (Tg) measurement, performed 40 days after total thyroidectomy for differentiated thyroid carcinoma and prior to the ablation of residual thyroid tissue by means of iodine-131 therapy. In a retrospective study we examined 334 consecutive patients followed up for 4–16 years by means of regular Tg measurements, ¹³¹I whole-body scans (WBS) and other diagnostic techniques, if necessary. In 79 patients metastases were discovered (32 lymph node and 47 distant metastases) within 18 months following thyroidectomy. Mean values of first Tg were significantly higher in patients with than in patients without metastases (258.9±310.6 vs 15.9±19.6 ng/ml; P<0.0001). Receiver operating characteristic (ROC) curve analysis of data revealed that for first Tg values higher than 69.7 ng/ml, the positive predictive value for the presence of metastases exceeded 90%. No statistically significant correlation was found between first Tg value and either thyroid-stimulating hormone (TSH) value or percentage of ¹³¹I uptake by residual thyroid tissue. No other parameter (age, histological type, site of metastases, ¹³¹I uptake by metastases) was significantly related to the first Tg value. We conclude that the first Tg measurement after total thyroidectomy provides a useful early diagnostic indication of metastatic disease in spite of the presence of a post-surgical thyroid remnant, and that this holds true regardless of the TSH value and WBS result. This early information is of clinical relevance for patient follow-up. Received 26 October 1998 and in revised form 12 June 1999     

Radioiodine treatment of non-toxic multinodular goitre: effects of combination with lithium

Purpose This study aimed to evaluate the effects of radioiodine (¹³¹I), alone or in combination with lithium, on thyroid volume and the prevention of radioiodine-induced thyrotoxicosis. This is the first clinical trial including only patients with multinodular goitre, normal TSH values and negative anti-thyroid auto-antibodies at baseline.Methods Eighty consecutive patients were randomised to receive ¹³¹I plus lithium (group I+L) or ¹³¹I alone (group I). Thyroid ultrasonography and biochemical analyses were performed at baseline and at 1, 3, 6, 12 and 24 months after treatment.Results At 1–4 weeks after treatment, ¹³¹I-induced hyperthyroidism was observed in 58.8% of patients and was prevented by lithium administration. A low incidence of hypothyroidism (19%) was recorded at 24 months, whereas up to 44% of patients developed anti-thyroid antibodies. A significant reduction in thyroid volume was observed after ¹³¹I, with a mean decrease of 47.2% (median 48.2%) at 24 months, without differences between the groups. Moreover, it was shown that the decrease in thyroid volume after ¹³¹I was also due to the significant shrinkage of thyroid nodules.Conclusion This demonstrates that adjunctive lithium is able to reduce radioiodine-induced hyperthyroidism. Therefore, such treatment appears to be safe in older patients and those with underlying cardiovascular disease. In the present large series, ¹³¹I therapy was demonstrated to be highly effective in reducing thyroid and nodular volume even in patients treated with low ¹³¹I doses (2.5 MBq/ml of thyroid tissue), further supporting the view that radioiodine therapy represents a real alternative to surgery.     

131I不同剂量法治疗甲亢疗效对比

目的 比较131I固定剂量法和计算剂量法治疗甲亢的近期疗效。方法 148例甲亢患者随机分配为固定剂量组和计算剂量组,131I治疗后6个月随访,检测患者血清促甲状腺激素(TSH)、游离三碘甲腺原氨酸(FT₃)和游离甲状腺素(FT₄)水平,评价131I治疗效果。结果 131I治疗后6个月固定剂量组、计算剂量组甲减发生率分别为31.1%、28.4%,统计学差异无意义(χ2=0.742,P=0.528),总治愈率分别为93.3%、85.2%,统计学差异无意义(χ2=0.958,P=0.403)。不同治疗结果(甲亢、甲状腺功能正常和甲减)之间甲状腺质量的统计学差异有意义(F=13.639,P=0.000),患者年龄、24h甲状腺吸碘率(RAIU)统计学差异无意义(F=1.374,P=0.241;F=2.534,P=0.137)。结论 131I固定剂量法简化治疗步骤,节约治疗费用,是值得提倡的治疗方法。     

Intraoperative gamma probe guidance with 99mTc-pertechnetate in the completion thyroidectomy

Aim  Intraoperative gamma probe (GP) guidance with ^99mTc-pertechnetate in the completion total thyroidectomy after a first thyroidectomy was investigated in this prospective study. Methods  The study group comprises of fourteen consecutive patients (14 females, age mean 50.2 ± 12.0 years, age range 29–73 years). All patients underwent a second thyroidectomy due to inadequate (5/14 patients) and complementary (9/14 patients) interventions. Serum-free three iodothyronine, free thyroxin and thyroid stimulating hormone measurements, a neck ultrasonography (USG) and thyroid scintigraphy (TS) were performed in the preoperative and postoperative period. After a 185 MBq (5 mCi) injection of ^99mTc-pertechnetate, background (BG), left thyroid lobe (LTL), right thyroid lobe (RTL) and pyramidal tyroid lobe (PTL) regions were counted in time before and after resection of thyroid remnants by intraoperative GP. All resection materials were evaluated by histopathologic examination. Results  Preoperative TSH was less than 30 mIU/mL (mean 21 ± 7) in all patients. Functioning thyroid remnants were shown in 13/14 patients on the preoperative TS and USG, which were diagnosed by USG in one but by TS in other one. We calculated that percentage median (minimum–maximum) values were 220.90% (56.00–411.11%) in LTL, 80.43% (11.54–471.05%) in RTL and 66.60% (−3.33 to 158.33%) in PTL for counts before resection, on the other hand, 15.96% (−20.55 to 47.62%) in LTL, 17.59% (−15.07 to 38.46%) in RTL and 17.59% (−1.96 to 57.14%) in PTL regions for counts after resection. There were statistically significant differences between these values belonging to before and after resection for LTL (p = 0.001), RTL (p = 0.001) and PTL (p = 0.008). Bilateral small foci in a patient and unilateral focus in other patient were observed in postoperative TS. Unilateral focus was detected on the RTL by GP, but not bilateral foci. Postoperative TSH levels increased to 30 mIU/mL (mean 69 ± 26) at least. There was a statistically significant difference between preoperative and postoperative TSH values (p < 0.001). Histopathologic confirmation revealed that all removed materials were the thyroid tissues. Conclusions  Gamma probe guidance with ^99mTc-pertechnetate seemed to be a good option and easy available method in patients undergoing the completion total thyroidectomy.     

Outcome of radioiodine therapy without, on or 3 days off carbimazole: a prospective interventional three-group comparison

Purpose Carbimazole ameliorates hyperthyroidism but reduces radioiodine uptake and adversely affects the outcome of simultaneous radioiodine therapy. We explored whether withdrawal of carbimazole for 3 days can restore the outcome of radioiodine treatment without concurrent exacerbation of hyperthyroidism. By generating three groups with comparable radioiodine uptake, we also investigated whether the effect of carbimazole depends on the radioiodine uptake.Methods Stratified by a radioiodine uptake >30%, 227 consecutive adult patients were prospectively assigned to radioiodine therapy (target dose 200 Gy) without, on or 3 days off carbimazole. Patients were clinically (Crooks-Wayne score) and biochemically (T₃, fT₄, TSH) followed up after 3, 6 and 12 months. Primary endpoint was outcome 12 months after radioiodine therapy.Results A total of 207 patients completed follow-up (toxic nodular goitre, n=117; Graves’ disease, n=90). The overall success rate was 71.5%. Patients without and 3 days off carbimazole had similar biochemical (81.4% and 83.3%, respectively; p=0.82) and clinical outcomes [median (range) Crooks-Wayne score 0 (0–16) and 1 (0–10), respectively; p=0.73], which were both higher than in patients on carbimazole [42.6%, p<0.001; Crooks-Wayne score 3 (0–30), p<0.03]. Time to achieve cure was delayed on carbimazole. No changes in thyroid hormone levels occurred after 3 days’ discontinuation of carbimazole. Logistic regression revealed that all observed cure rates were independent of entity, sex, age, thyroid volume, radioiodine uptake, radioiodine half-life, fT₄, T₃ and TSH.Conclusion Patients under carbimazole treatment can be referred for radioiodine therapy after withdrawal of carbimazole for only 3 days. Three days of carbimazole withdrawal is long enough to restore the success of radioiodine therapy and short enough to avoid the risk of exacerbation of hyperthyroidism.     

Comparison of radioiodine biokinetics following the administration of recombinant human thyroid stimulating hormone and after thyroid hormone withdrawal in thyroid carcinoma

Iodine kinetics were studied in patients with differentiated thyroid cancer while euthyroid under exogenous thyroid stimulating hormone (TSH) and while hypothyroid to detect differences in radioiodine uptake, distribution and elimination. Nine patients with total or near-total thyroidectomy on thyroid hormone suppressive therapy received two or three daily doses of 0.9 mg recombinant human TSH (rhTSH) followed by administration of a diagnostic activity of 2 mCi (74 MBq) iodine-131. After the biokinetics assessments had been performed, patients stopped taking thyroid hormones to become hypothyroid. A second 2 mCi (74 MBq) diagnostic activity of ¹³¹I was administered, followed by a second set of biokinetics assessments. One week later the patients underwent remnant ablation with a therapeutic activity of ¹³¹I. A comparison of the ¹³¹I kinetics in the patients while euthyroid and while hypothyroid showed major differences in the doses to the remnant as well as in residence times and radiation exposure to the blood. In the first diagnostic assessment the remnant dose was higher in eight of the nine patients and clearance of the activity from the blood was faster in all of them. The data from this study suggest that radioiodine administration is potent and safe when administered to euthyroid patients following rhTSH administration. Enhanced residence time in the remnant and decreased radiation exposure to the blood were noted when patients were euthyroid compared to when they were rendered hypothyroid. However, all patients received diagnostic activities in the same order: first while euthyroid, followed by hypothyroidism. It is quite possible that "stunning" from the radioiodine administered in the initial uptake study inhibited the subsequent uptake of radioiodine by the remnant lesions in the second uptake study.     

Serial TSH determination after T3 withdrawal or thyroidectomy in the therapy of thyroid carcinoma

Exogenous triiodothyronine (T3) was substituted for levothyroxin or desiccated thyroid in 13 athyrotic patients previously treated for papillary, follicular, or mixed papillary-follicular carcinoma of the thyroid. After 4 weeks T3 therapy was discontinued and serial determinations of plasma thyroid stimulating hormone (TSH) concentrations were made. A roughly exponential rise in TSH values, corresponding to a doubling time of 2 days, was observed until a level of 40 microIU/ml was reached, after which the curve passed through a maximum at 20 days. The mean time required for a level of 50 microIU/ml was 11 days, and this time is suggested for TSH determination before I-131 imaging of patients with thyroid cancer. Plasma TSH values in eight patients following "total" thyroidectomy showed a much slower and more variable rise, with a mean doubling time of 7.6 days. Weekly TSH levels beginning at 15 days will provide a rational basis for I-131 imaging in this group, in whom a longer period of hypothyroidism will be required before imaging and therapy. Adherence to these protocols should minimize the duration of hypothyroidism in patients undergoing I-131 treatment of thyroid carcinoma.     

Judicious use of recombinant TSH in the management of differentiated thyroid carcinoma

Objective  

To evaluate the feasibility of using recombinant human TSH (rhTSH) in conjunction with ¹³¹I to treat patients with differentiated thyroid carcinoma.