甲状腺部分切除术后甲状腺功能减退的相关原因分析

目的　探讨继发于部分甲状腺 ( 5 0 %～ 70 % )切除术后甲状腺功能减退 (甲减 )的发病率和相关原因。方法　回顾性分析 1988～ 2 0 0 0年行部分甲状腺切除术 12 10例患者的临床资料 ,包括年龄、性别、血清TSH水平、甲状腺球蛋白抗体 (TGA )、甲状腺过氧化物酶抗体 (TPO )、切除甲状腺组织重量等 ,以确定外科术后甲减的发生率和相关原因。结果　 12 10例中有 41例 ( 3 .4% )诊断为甲减 ,其中亚临床甲减 2 8例 ,临床甲减 13例。术后TSH平均水平为 ( 9.2 2± 3 .3 6)mU /L。与甲状腺功能正常患者的术前TSH水平 [( 1.0 7± 0 .72 )mU /L]相比 ,甲减者术前TSH平均水平 [( 3 .14±1.0 5 )mU /L ]明显升高 (P 0 .0 5 ) ;术前、术后的TGA及TPO水平比术后功能正常者明显升高 (P 0 .0 5 )。在年龄、性别或切除甲状腺组织重量上无显著性差异。平均甲状腺片的有效治疗剂量为1mg/ (kg·d) [范围 0 .3～ 1.3mg/ (kg·d) ]。 结论　继发于部分甲状腺切除术后的甲减常见于术前TSH和甲状腺自身抗体水平较高的病例 ,而与年龄、性别或切除甲状腺组织重量等因素无关 ,通常是症状轻微或无症状者 ,且用小剂量的甲状腺激素治疗效果良好。     

Methimazole Slows Hepatocyte Streaming in Rats

Hepatocytes are hypothesized to continuallystream from the portal tract to the terminal hepaticvein. By this model, when a cell divides, one of itsprogeny replaces the dividing ancestor and the other is displaced into a more remote location. Thepresent experiment aims to demonstrate thathypothyroidism affects liver cell turnover. Thirty maleadult rats were divided into two groups. One receivedmethimazole for two weeks and the other served as control.Each rat was injected intraperitoneally with 18.5 KBq[³H]thymidine/g body weight. Rats were killedafter 1 hr and two and four weeks. Autoradiography was done. The distance of the labeled cells fromthe portal tract was measured. The mean TSH levels ofthe methimazole-treated group and controls were 1.45 and0.25 mM/liter, respectively (P < 0.01). Hepatocyte streaming was lower in hypothyroid (1.8m/day) than in untreated rats (2.5 m/day) (P< 0.01). The respective labeling indices 1 hr afterlabeling were 0.9% and 1.24% (P < 0.05). We concludethat hypothyroidism diminishes hepatocyte and littoral cellturnover and slows down their streaming.     

Thyroid function and postmenopause

There is an increasing prevalence of high levels of thyroid stimulating hormone (TSH) with age - particularly in postmenopausal women - which are higher than in men. The incidence of thyroid disease in a population of postmenopausal women is as follows: clinical thyroid disease ,about 2.4%; subclinical thyroid disease ,about 23.2%. Among the group with subclinical thyroid disease ,73.8% are hypothyroid and 26.2% are hyperthyroid. The rate of thyroid cancer increases with age. The symptoms of thyroid disease can be similar to postmenopausal complaints and are clinically difficult to differentiate. There can also be an absence of clinical symptoms. It is of importance that even mild thyroid failure can have a number of clinical effects such as depression ,memory loss ,cognitive impairment and a variety of neuromuscular complaints. Myocardial function has been found to be subtly impaired. There is also an increased cardiovascular risk ,caused by increased serum total cholesterol and low-density lipoprotein cholesterol as well as reduced levels of high-density lipoprotein. These adverse effects can be improved or corrected by L-thyroxine replacement therapy. Such treatment has been found to be cost-effective. With time ,overt hypothyroidism can develop. Therefore ,routine screening of thyroid function in the climacteric period to determine subclinical thyroid disease is recommended. Hormone replacement therapy (HRT) in women with hypothyroidism treated with thyroxine causes changes in free thyroxine and TSH. Increased binding of thyroxine to elevated thyroxine-binding globulin causes an elevation of TSH by feedback. Since adaptation is insufficient ,there is an increased need for thyroxine in these women taking HRT. TSH levels should be controlled at 12 weeks after the beginning of therapy. At higher age the need for iodine and thyroxine is decreased. Therefore ,therapy has to be controlled. For bone metabolism thyroid hormones play a dominant role. While there are only marginal differences between hypothyroid patients and euthyroid controls ,there are large differences for hyperthyroid patients. Previous thyrotoxicosis and subsequent long-lasting L-thyroxine treatment are together associated with reduction in femoral and vertebral bone density in postmenopausal women. In these cases HRT is important for the control of bone loss.     

Hypothyroidism Protects Rat Liver from Acetaminophen Hepatotoxicity

Recent data from animal studies suggest thatinduced hypothyroidism inhibits the development of liverinjury in several animal models, including livercirrhosis and fulminant hepatic failure in rats, and immune-mediated acute liver injury in mice. Theaim of the present study was to determine whetherhypothyroidism would likewise preventacetaminophen-induced hepatic damage in rats. Liverdamage was induced by acetaminophen (2 g/kg) administered bygavage to fasting rats as a single dose. Hypothyroidismwas induced by methimazole, propylthiouracil, orsurgical thyroidectomy and confirmed by elevated serum levels of TSH. Hypothyroidism significantlyinhibited acetaminophen-induced liver damage asmanifested by the decreased serum levels of liverenzymes, malondialdehyde and blood ammonia, as well asby the higher hepatic glutathione content, in allthree groups of hypothyroid rats compared to euthyroidcontrols (P < 0.01). Histopathologic analysis showedsignificantly less liver necrosis and inflammation in the acetaminophen-treated hypothyroid rats.Oxygen extraction, measured in isolated perfused ratliver preparation, was also reduced in the hypothyroidlivers to 42 ± 8% compared to 81 ± 14% ofcontrols (P < 0.01). However, the expression ofCYP2E1 in the livers of hypothyroid rats, as measured bywestern blot analysis, was not decreased compared tocontrol rats. These results suggest that inducedhypothyroidism, regardless of the mode of induction, protectsrat liver from acetaminophen hepatotoxicity. This effectmay be related to hypometabolism of liver cells, but theexact mechanism needs further clarification.     

温肾助阳药对甲状腺切除兔体内镁含量变化的影响

采用电感耦合等离子体原子发射光谱法，对甲状腺全切除兔（甲低组）、甲状腺切除后灌服温肾助阳方药兔（中药组）以及对照组兔背毛、血清、肝脏和脑组织中镁含量的变化进行检测。结果表明，甲低组背毛镁值术后明显低于术前；中药组背毛镁值无明显减少，但术后３４天其肝和脑镁含量明显低于对照组。提示中药对甲低病体镁元素的代谢和分布有明显影响。     

Hemostatic changes in thyroid diseases

Several studies have reported hemostatic abnormalities, both in terms of bleeding or thrombosis, in patients with various thyroid dysfunctions. The aim of this review is to briefly discuss the relationship between thyroid disorders and hemostasis (i.e. primary hemostasis, coagulation factors and fibrinolytic system). From the analysis of the more recent literature data, it appears evident that most of the coagulation abnormalities associated with thyroid disorders are a consequence of a direct action of thyroid hormones on the synthesis of various hemostatic factors or a derangement of immune function. On the whole, these data suggest that a hypercoagulable state is present in hyperthyroid patients, while patients suffering from moderate hypothyroidism are at increased risk of thrombosis contrasting with the bleeding tendency of those presenting severe hypothyroidism.     

Thyroid autoimmunity and infertility

We aimed to study the prevalence of thyroid autoimmunity in infertile women; to assess whether thyroid autoantibodies were associated with non-organ-specific autoantibodies; and to investigate the influence of this dysfunction on the couples' chances of pregnancy. We assayed serum levels of thyroid stimulating hormone (TSH) ,free thyroxine ,and microsomal and thyroglobulin autoantibodies in 149 infertile women. In patients with serum TSH levels in the hypothyroid or hyperthyroid range and/or with thyroid autoantibodies ,we performed thyroid ultrasound examinations and assayed some non-organ-specific autoantibodies. We compared the duration of infertility in infertile patients with normal thyroid (control group) ,with thyroid abnormalities ,and with thyroid autoantibodies in euthyroidism. Thirty infertile patients (20.1%) had thyroid abnormalities. The prevalence of thyroid autoantibodies was 17.4%. In infertile patients with thyroid autoantibodies ,we found a poor association with non-organ-specific autoantibodies. Only the women with thyroid abnormalities and ovulatory dysfunction had a mean duration of infertility significantly longer than that of the control group. When the data were analyzed for euthyroid women with thyroid autoantibodies ,we found no significant variation in the duration of infertility. Although we found a high prevalence of thyroid autoantibodies in infertile patients ,the presence of these autoantibodies per se did not reduce the chance of pregnancy.     

电针对甲状腺功能低下大鼠神经内分泌的调节作用

观察电针对甲状腺功能低下大鼠血清甲状腺和性腺激素、下丘脑和垂体β－内啡肽（β－ＥＰ）及血浆环核苷酸含量的影响。结果表明：电针能调节甲状腺功能低下大鼠血清Ｔ３和睾酮含量,下丘脑β－ＥＰ和血浆环核苷酸可能参与这一作用。     

Prevalence of Subclinical Hypothyroidism in a Morbidly Obese Population and Improvement after Weight Loss Induced by Roux-en-Y Gastric Bypass

Background:There are many studies concerning thyroid function in obesity, and some of them describe higher TSH levels in obese subjects. Few studies evaluated long-term changes in thyroid function caused by weight loss after bariatric surgery. Our aims were to evaluate the prevalence of subclinical hypothyroidism (SH) in a morbidly obese population and to analyze the effect of weight loss induced by Roux-en-Y gastric bypass (RYGBP) on TSH and thyroid hormone (TH) levels. Methods: TSH, free thyroxine (fT4) and total triiodothyronine (T3) levels were analyzed before and 12 months after RYGBP in patients with grade III or grade II obesity with co-morbidities. Subjects taking TH and/or with positive antithyroid antibodies and/or with overt hypothyroidism were excluded. Results: 72 subjects (62F/10M), with mean age 39.6±9.8 years and mean BMI 53.0±10.4 kg/m² were studied. The prevalence of SH before RYGBP was 25% (n=18). There was a significant post-surgical decrease in BMI in the whole population, as well as in SH patients. In the SH group and normal TSH group, there was a decrease in TSH and T3, but not in fT4. TSH was not correlated with initial BMI or percent change in BMI. TSH concentrations reached normal values in all SH patients after RYGBP. Conclusion: Our data confirm that severe obesity is associated with increased TSH. The decrease in TSH was independent of BMI, but occurred in all SH patients. A putative effect of weight reduction on the improvement of SH in all patients may be an additional benefit of bariatric surgery.