Thyroid function after surgery for autonomous and non-autonomous nodular endemic goitre — effect of iodide-substitution

Summary The aim of this study was to evaluate the influence of postoperative iodide-substitution on the function of thyroid remnants of different quality and quantity in order to define the appropriate prophylaxis (iodide or thyroid hormone) to prevent recurrent goitre.In a prospective, randomized clinical trial, the following patients were examined:group I: simple, non-autonomous nodular goitre, bilateral thyroidectomy (n=40);group II: simple, non-autonomous nodular goitre, selective (unilateral) thyroidectomy (n=40);group III: autonomous nodular goitre, bilateral thyroidectomy (n=40);group IV: autonomous nodular goitre, selective (unilateral) thyroidectomy (n=35). The following parameters were measured 6 and 12 weeks postoperatively. Serum-total-T₄, -T₃,-TSH, TRH-test, 99^mTc-Thyroid-Uptake (TcTU). Six weeks postoperatively the 4 groups were separately randomized into controls and treatment groups, who received 200 µg iodide/day orally. Six weeks postoperatively, patients in group I had lower T4 levels and both basal and stimulated TSH were higher than in the other groups, however no significant differences were observed in T₃, T₄/T₃ ratio and TcTU.Twelve weeks postoperatively patients from groups I, II and III, who had been treated with iodide, had lower T₃ and TcTU values but higher T₄ and T₄/T₃ than the appropriate controls. Basal and stimulated TSH showed no differences between controls and iodide-treated patients in these groups. In group IV, T₄ and T₃ showed a tendency to elevation (n.s.), and basal and stimulated TSH as well as TcTU were lower in patients with iodide.Iodide-substitution (200 µg/day) has no major influence on the pituitary-thyroid axis, except after selective surgery for autonomous nodular goitre (group IV). Generally, iodide treatment abolishes the symptoms of iodine-deficiency, improving the autoregulatory capacity of the thyroid remnant. It could replace thyroid hormone as a prophylaxis against recurrent goitre in the majority of patients after selective thyroid surgery.Abbreviations AFTT Autonomously Functioning Thyroid Tissue - TcTU 99^mTc-Thyroid-Uptake - TRH TSH-Releasing-Hormone - TSH Thyroid-Stimulating-Hormone - T₃ Triiodothyronine - T₄ Thyroxine     

Thyroid function after surgical treatment of nontoxic goitre. A randomized study of postoperative thyroxine administration

Following thyroid resection for nontoxic goitre, 29 euthyroid patients were randomly allocated to no medication or to 0.2 mg levothyroxine daily (17 and 12 patients). The two groups were comparable in age, sex, extent of surgery and thyroid pathology. The patients were free from other endocrine disorders and had no other medication. Serum TSH, T4 and T3 were measured and T3-resin test performed preoperatively and 14 days and 3, 6, 12 and 18 months postoperatively. All values were within normal range. Only at the 3-month follow-up could statistically significant intergroup differences be observed, with T4 higher in the thyroxine-treated and TSH higher in the untreated group, but the outset values were thereafter regained. The T3 values in both groups were slightly reduced immediately after the operation. There was no recurrence of goitre in the 18-month observation period, and none of the findings suggested that routine thyroxine treatment is of value after resection of nontoxic goitre "in Denmark".     

Autoantibodies in iodide goitre and asthma

Thyroid and gastric autoimmunity occurred more frequently in patients with iodide goitre and those with intrinsic asthma than in patients with extrinsic asthma or age- and sex-matched controls. It is suggested that iodide administration is more likely to lead to goitre and hypothyroidism in the intrinsic asthmatic group, where latent thyroid autoimmunity is common, by aggravation of an existing organification defect in the thyroid. Latent Graves' disease recognized by failure of suppression of the thyroid radioiodine uptake by triiodothyronine may also be responsible for some cases of iodide goitre.     

Occurrence of ophthalmopathy after treatment for Graves' hyperthyroidism. The Thyroid Study Group.

BACKGROUND. Ophthalmopathy caused by Graves' disease may first appear or worsen during or after treatment for hyperthyroidism. It is not known, however, whether choosing to treat hyperthyroidism with antithyroid drugs, iodine-131, or surgery affects the development or aggravation of Graves' ophthalmopathy. METHODS. We studied 168 patients with hyperthyroidism caused by Graves' disease, stratified into two age groups--20 to 34 years (54 patients, group 1) and 35 to 55 years (114 patients, group 2). The patients in group 1 were randomly assigned to treatment with methimazole for 18 months or subtotal thyroidectomy, and those in group 2 to either of these two treatments or to iodine-131 therapy. All the patients received thyroxine to avert hypothyroidism, except those treated with iodine-131, who received thyroxine only if hypothyroidism developed. The duration of follow-up was at least 24 months. RESULTS. Twenty-two patients (13 percent) had infiltrative Graves' ophthalmopathy at randomization. During follow-up, ophthalmopathy developed for the first time in 22 patients (13 percent) and worsened in 8 patients (5 percent). The frequency of the development or worsening of ophthalmopathy was similar among the patients in group 1 (medical therapy, 4 of 27 patients [15 percent]; and surgery, 3 of 27 patients [11 percent]). In group 2, ophthalmopathy developed or worsened in 4 of the 38 patients (10 percent) treated medically, 6 of the 37 patients (16 percent) treated surgically, and 13 of the 39 patients (33 percent) given iodine-131 (P = 0.02 for the comparison between the iodine-131 subgroup and the others combined). The risk of the development or worsening of ophthalmopathy increased as pretreatment serum triiodothyronine concentrations increased. CONCLUSIONS. As compared with other forms of antithyroid therapy, iodine-131 is more likely to be followed by the development or exacerbation of Graves' ophthalmopathy.     

Thyroid tumours of uncertain malignant potential: frequency and diagnostic reproducibility

The term thyroid tumours of uncertain malignant potential (TT-UMP) has been proposed for a subgroup of follicular-patterned thyroid tumours for which benignancy or malignancy cannot be assessed with certainty. The frequency, diagnostic reproducibility, immunohistochemistry and molecular genetic profiling of such tumours have been poorly explored. We, therefore, investigated (1) the frequency of TT-UMP diagnosed in a single institution (Nice, France: 2004–2008), (2) the observer variation among four pathologists, (3) whether immunohistochemical and molecular genetic profiling of TT-UMP provide additional information concerning such lesions. A series of 31 diagnosed TT-UMP (2.9%) out of 1,078 consecutive thyroidectomies were analysed. It comprised 15 follicular thyroid tumours of UMP (FT-UMP) and 16 well-differentiated tumours of UMP (WDT-UMP). Observer concordance was 70% for all TT-UMP. More than 50% of FT-UMP expressed galectin-3 and CK19, whereas more than 50% of WDT-UMP expressed HBME-1. Five cases of TT-UMP showed N-RAS mutations, while one showed H-RAS mutation and another PAX8/PPARγ rearrangement. In conclusion, the frequency of TT-UMP is low in our institution. Diagnostic reproducibility is within the same range as other published data on follicular-patterned thyroid tumours. The ancillary methods have a low impact on aiding diagnosis of such lesions.     

Changes in myocardial cell size and number during the development and reversal of hyperthyroidism in neonatal rats

Increased workload was produced in newborn rats to study myocyte structure during conversion from hyperplastic to hypertrophic growth. Newborn rats were given L-thyroxine (T4) for 12 days and killed at that time or 20 days after discontinuing T4 treatment. Myocytes were isolated by a perfusion technique with collagenase. Cellular dimensions were determined with a sonic digitizer. Mean cell volumes were also determined with a Coulter counter for comparison with values obtained with the digitizer. Heart weight to body weight ratios were increased 30% in 12-day-old hyperthyroid rats. Cell length increased 22%, and cell volume increased 31% after 12 days of treatment with T4. The calculated number of ventricular myocytes indicated that T4 inhibited rather than stimulated hyperplastic myocyte growth. Twenty days after discontinuing T4 treatment, heart weight to body weight ratio and mean cell volume of treated animals were similar to control values. Cell length, however, remained significantly increased (14%), and cell width was significantly reduced (8%) after reversal of hyperthyroidism. We conclude that excess T4 inhibits hyperplastic myocyte growth in neonatal rats while stimulating hypertrophy of existing myocytes primarily by increasing cell length. Myocytes remained significantly longer after reversal of hyperthyroidism, indicating that structural changes may persist.     

Nuclear segmentation in goitre aspirates.

Nuglear segmentation was studied in fine needle aspirate smears from toxic and atoxic goitres. The smear technique implies a flattening of the nuclei on a slide, which facilitates detection of nuclear segmentation. Such segmentation was found in 2.2% of the nuclei in toxic goitres and in 0.9% in atoxic goitres. The difference was highly significant p less than 0.001. The segmented cells were usually of uniform appearance with one large and one small segment. Only very rarely were more than two segments seen.     

B- and T-lymphocytes in toxic diffuse goitre.

Operation specimens of thyroid tissue from patients with Graves' disease were digested, with collagenase, down to a cell suspension. The lymphocytes in the suspension were concentrated by density-gradient sedimentation and the proportions of B and T lymphocytes were determined. Six patients with Graves' disease were studied. The proportions of B and T lymphocytes in the thyroid glands were similar to the proportions of B and T lymphocytes in the venous blood from healthy subjects.     

数字PCR中微滴生成尺寸与频率的数值模拟

目的微滴合成是数字PCR中的关键技术,但其中两相流速与生成微滴大小和频率的关系尚不明确。本文采用VOF模型研究数字PCR系统中生成微滴的尺寸、频率与两相流速的关系。方法将氟化油作为连续相,反应液(水)作为离散相,通过求解整体的动量方程和各自相的体积分数连续方程来实现相与相间的界面追踪,模拟出微通道内两相的流动情况,对不同两相流速下微通道内微滴生成的尺寸和频率进行研究。结果在不同的流速条件下,微通道内会出现弹状流、滴状流和管状流3种流型。并且,对于弹状流和滴状流,随着连续相流速的增加,微液滴的生成尺寸减小,生成频率增加;而随着离散相流速的增加,微液滴的生成尺寸和频率都会增加。结论在滴状流状态下,当连续相流速为0.048~0.064 m/s,并且离散相流速为0.016~0.032 m/s时,可高效生成数字PCR微滴。     

Thyroid size determined by ultrasound. Influence of physiological factors and non-thyroidal disease

Grading of goitre size according to WHO or the palpatory estimation of thyroid volume does not allow a quantitative estimation of thyroid size or an objective follow-up during treatment with e.g. radioiodine. The present and other studies have demonstrated that the ultrasonic evaluation of thyroid volume is both accurate and precise. In addition, it is non-invasive, rapid, inexpensive and without discomfort to the patient. Using this technique it was demonstrated that thyroid volume increases with increasing age and body weight in both sexes, with weight having the most pronounced influence. The relationship between thyroid volume, body weight and age in non-goitrous healthy subjects can be described using a formula that allows the calculation of normal thyroid size for a population: Thyroid volume (ml) = 1.97 + 0.21 x bodyweight (kg) + 0.06 x age (years). Cigarette smoking is associated with an approximately 10-fold increase in goitre frequency probably due to a combination of an increased sympathetic stimulation of the thyroid and an iodine deficiency state caused by inhalation of thiocyanate. Although no seasonal alteration in serum TSH level could be demonstrated thyroid volume is 23% higher in the winter than in the summer. Cyclic alterations of thyroid volume possibly related to TSH alterations have been found with a 50% difference between minimum values in the first half and maximum values in the second half of the menstrual cycle. Nonthyroidal illnesses are associated with marked alterations in thyroid volume. Thus, chronic renal disease and acute hepatic disease demonstrate significant increases in thyroid volume although the precise mechanisms have not been clarified. Chronic hepatic disease per se and chronic nonrenal nonhepatic disease does not seem to influence thyroid volume. Chronic alcoholism, however, with or without liver cirrhosis is associated with a marked decrease in thyroid volume and an increase in the amount of fibrosis probably related to a direct toxic effect of alcohol on the thyroid. All these factors should be kept in mind when goitre frequency, goitrogenic action of drugs and goitre treatment effects are evaluated.     

Impedance modulation and feedback corrections in tracking targets of variable size and frequency

Humans are able to adjust the accuracy of their movements to the demands posed by the task at hand. The variability in task execution caused by the inherent noisiness of the neuromuscular system can be tuned to task demands by both feedforward (e.g., impedance modulation) and feedback mechanisms. In this experiment, we studied both mechanisms, using mechanical perturbations to estimate stiffness and damping as indices of impedance modulation and submovement scaling as an index of feedback driven corrections. Eight subjects tracked three differently sized targets (0.0135, 0.0270, and 0.0405 rad) moving at three different frequencies (0.20, 0.25, and 0.33 Hz). Movement variability decreased with both decreasing target size and movement frequency, whereas stiffness and damping increased with decreasing target size, independent of movement frequency. These results are consistent with the theory that mechanical impedance acts as a filter of noisy neuromuscular signals but challenge stochastic theories of motor control that do not account for impedance modulation and only partially for feedback control. Submovements during unperturbed cycles were quantified in terms of their gain, i.e., the slope between their duration and amplitude in the speed profile. Submovement gain decreased with decreasing movement frequency and increasing target size. The results were interpreted to imply that submovement gain is related to observed tracking errors and that those tracking errors are expressed in units of target size. We conclude that impedance and submovement gain modulation contribute additively to tracking accuracy.     

HLA and hyperthyroidism in Ireland

The distribution of HLA antigens in a group of Irish patients with hyperthyroidism was studied, in an attempt to define whether specific antigens were associated with relapse of the disease following medical therapy. The increase in HLA-B8 and DR3 found by others in this disease was confirmed, but no difference in HLA type was documented in 33 patients who had relapsed compared to 24 who had not relapsed. Forty-six per cent of the relapsed group were DR3 as against 45% of the non-relapsed group.     

Hyalinizing trabecular adenoma-like lesion in multinodular goitre

Hyalinizing trabecular adenoma, a recently characterized variant of thyroid adenoma, is often confused with a variety of lesions because of its unusual histological features (Carney, Ryan & Goellner 1987). We report a case of multinodular goitre in which there were several small nodules showing features of hyalinizing trabecular adenoma and peculiar nuclear rods.     

Intranodular reactive endothelial hyperplasia in adenomatous goitre

Endothelial hyperplasia has rarely been recognized in the thyroid. Ischaemic events or hemorrhage, sometimes as a result of fine needle aspiration procedures, have been regarded as possible causes. To clarify the morphological pattern and the clinical significance of this lession, we studied a series of adenomatous goitres and selected 11 cases showing prominent endothelial hyperplasia in an individual nodule. Grossly, the parenchyma of the affected nodule was substituted by greyish, friable tissue surrounded by a fibrous capsule and by a thin rim of residual thyroid parenchyma. Microscopically, fibrinous and haemorrhagic material was crossed by intercommunicating vascular channels or papillary structures. These were lined by plump endothelial cells. In only one case had pre-operative fine needle aspiration biopsy been performed: smears yielded a haemorrhagic background, fibrin and numerous elongated cells; colloid and follicular cells were virtually absent. In both surgical and cytological specimens a differential diagnosis with a vascular neoplasm, a rare occurrence in the thyroid, was taken into consideration. We conclude that intranodular reactive endothelial hyperplasia is a relatively common occurrence (1.6%) in adenomatous goitre and is of diagnostic interest in both surgical and cytological specimens, since it can mimic vascular tumours and may lead to unnecessary treatment if misdiagnosed.