The pituitary-thyroid axis in patients with pituitary disorders

The pituitary-thyroid axis of 12 patients, exposed to transsphenoidal pituitary microsurgery because of nonfunctioning adenomas (6), prolactinomas (3) and craniopharyngioma (1), or to major pituitary injury (1 apoplexy, 1 accidental injury), was controlled more than 6 months following the incidents. The patients did not receive thyroid replacement therapy and were evaluated by measurement of the serum concentration of thyroxine (T4), 3,5,3'-triiodothyronine (T3), 3,3',5'-triiodothyronine (rT3), T3-resin uptake test and thyrotropin (TSH, IRMA method) before and after 200 micrograms thyrotropin releasing hormone (TRH) iv. The examination also included measurement of prolactin (PRL) and cortisol (C) in serum. Apart from 1 patient with pituitary apoplexy all had normal basal TSH levels and 9 showed a significant TSH response to TRH. Compared to 40 normal control subjects the 12 patients had significantly decreased levels of T4, T3 and rT3 (expressed in free indices), while the TSH levels showed no change. Five of the patients, studied before and following surgery, had all decreased and subnormal FT4I (free T4 index) after surgery, but unchanged FT3I and TSH. The levels of FT4I were positively correlated to both those of FT3I and FrT3I, but not to TSH. The TSH and thyroid hormone values showed no relationship to the levels of PRL or C of the patients exposed to surgery. It is concluded that the risk of hypothyroidism in patients exposed to pituitary microsurgery is not appearing from the TSH response to TRH, but from the thyroid hormone levels.     

Thyroid functions in patients with various chronic liver diseases

In order to clarify an alteration in thyroid functions in patients with chronic liver diseases, serum total and free thyroxine (T4, FT4), total and free triiodothyronine (T3, FT3), total reverse T3 (rT3), thyrotropin (TSH), thyroxine-binding globulin (TBG) concentrations, and T3 uptake (T3U) were measured by radioimmunoassays in 53 patients with chronic hepatitis (CH), 24 patients with compensated liver cirrhosis (LC), 17 patients with hepatocellular carcinoma associated with LC (HCC), and 40 normal subjects. Serum T4, T3, and rT3 in CH, and serum rT3 in HCC were significantly increased, while serum T4 in LC and serum T3 in HCC were significantly decreased. Serum TBG was increased and T3U was decreased in these patients. Serum TBG in CH and LC correlated positively with transaminase, and inversely with prothrombin time. FT4 and T4/TBG ratios in CH and LC and FT3 and T3/TBG ratios in LC and HCC were significantly decreased. Although T4/TBG ratios in HCC and T3/TBG ratios in CH were significantly decreased, FT4 in HCC and FT3 in CH were not decreased. The ratio of rT3/T3 in CH and LC correlated with various liver function tests. FT3 in LC and HCC correlated inversely with BSP (45') and positively with KICG. No differences in serum TSH values were found between chronic liver diseases and normal subjects. From these results, it was concluded that the thyroid functions in patients with chronic liver diseases were affected by the decrease in serum thyroxine, elevated serum TBG, the degree of which is in proportion to that of the liver cell damage, and impaired peripheral conversion of T4 to T3, the degree of which is in proportion to that of the hepatic dysfunction.     

Clinical study on early changes in thyroid function of hyperthyroidism treated with propylthiouracil and a relatively small dose of iodide.

In order to compare the acute effects of three kinds of antithyroid agents of iodide (I-), propylthiouracil (PTU) and PTU combined with iodide (PTU+I-) on thyroid function in hyperthyroid patients with diffuse goiter, serum concentrations of thyroxine (T4), triiodothyronine (T3), T3-resin sponge uptake (T3-RU) and free thyroxine index (FT4I) were employed as thyroid function parameters. In the group given iodine (1 mg/day) as iodinated-lecithine, the initial values of T4, T3, T3-RU and FT4I were 20.9 +/- 1.6 microng/100 ml (T4), greater than 740 ng/100 ml (T3), 49.5 +/- 2.3% (T3-RU) and 14.7 +/- 1.8 (FT4I). At the end of one week of therapy, they decreased clearly to 15.6 +/- 2.2 microng/100 ml, 457 +/- 87 ng/100 ml, 42.2 +/- 4.0% and 9.7 +/- 2.4. The so-called "escape phenomenon" from iodide inhibition was observed in serum T4, T3-RU and FT4I values at the end of two weeks of iodide therapy, while serum T3 continued to decrease but the value of T3 was far outside of the normal range. In the PTU group (300 mg/day), thyroid function parameters were 22.5 +/- 0.8 microng/100 ml (T4), greater than 592 ng/100 ml (T3), 54.9 +/- 1.0% (T3-RU) and 18.7 +/- 1.0 (FT4I) before treatment. They decreased continually week by week. At the end of four-week treatment with PTU, the value of each thyroid function parameter was 11.1 +/- 1.9 microng/100 ml, 229 +/- 56 ng/100 ml, 36.6 +/- 4.4% and 5.7 +/- 1.7. In the group of hyperthyroidism simultaneously given both PTU and iodide (300 mg/PTU and 1 mg/iodine), these thyroid function parameters decreased as well as in the group treated with PTU alone for more than two weeks. More rapid or significant decrease of T4, T3, T3-RU and ft4i in PTU+I- group than in PTU group was observed in the present study. These results suggested strongly that iodide alone was not an adequate therapy for hyperthyroidism as well known and they were also compatible with the idea that the concomitant administration of PTU and iodide was more effective in the early phase of therapy of hyperthyroidism than PTU alone.     

Analysis of overall pathophysiological relationships between serum levels of TSH and thyroid hormones using a large laboratory database

Factors associated with the basal level of serum thyrotropin (TSH) were analyzed over a wide range of pathophysiological conditions by means of a large laboratory database on thyroid function. When data were analyzed two-dimensionally, serum TSH showed significant inverse correlations with total triiodothyronine (T3), free T3 index (FT3I), total thyroxin (TT4) and free T4 index (FT4I) in the order of increasing intensity. The three-dimensional analysis, however, revealed that 1) total hormone levels were actually unrelated to serum TSH when the levels of free hormone indices were held constant, 2) the relation between FT3I and TSH became obscure when the influence of FT4I was similarly removed. On the other hand, 3) the relation of FT4I with TSH was unaffected by the level of FT3I. These results suggest that free T4 is the main determinant of the serum TSH level. This study also implies that it is possible to use large amounts of laboratory data to elucidate the overall profile of a given patho-physiological system, whose structure is only partially revealed by conventional clinical or animal studies.     

Closer correlation between serum triiodothyronine and basal metabolic rate during antithyroid drug treatment in patients with Graves' disease.

The correlations between serum triidothyronine (T3), thyroxine (T4), 131I-triiodothyronine resin sponge uptake (RT3U) or free thyroxine index (T7) and the basal metabolic rate (BMR) during antithyroid drug treatment in 86 patients with Graves' disease were investigated. Although serum T3, T4, RT3U and T7 during therapy with MMI showed significant positive correlations with BMR, the coefficient of correlation (r = 0.6088, P less than 0.001) between T3 and BMR was the highest of all. While the normal range of BMR in control subjects was between -1.9 and +14.9 (the range of mean +/- SD), the corresponding values of T3, T4, RT3U and T7 calculated from the regression lines, ranged from 94.2 to 184.0 ng/dl, from 5.32 to 8.75 microgram/dl, from 26.5 to 28.9% and from 1.57 to 2.47 respectively. On the other hand, when the corresponding values of BMR to normal values of T3 (100-170 ng/dl), T4 (7.6-12.2 microgram/dl), RT3U (26.7-36.5% and T7 (2.29-3.49) in control subjects were calculated from the regression lines, the range of value obtained from the regression line of T3 coincided better with normal value of BMR in control subjects that those calculated from other regression lines (T4, RT3U and T7). These results suggest that serum T3 level would be a better index of evaluation of the thyroid function that T4 or RT3U in patients with Graves' disease under antithyroid drug treatment.     

Visfatin Levels in Subclinical Hypothyroidism

Alterations in thyroid function are associated with changes in body weight, metabolism, and low-grade inflammation abnormal thyroid function may be associated with disturbances in the production of adipokines also. Although there have been studies showing changes in visfatin levels in thyroid dysfunction, exact relationship between them was still unclear. Our aim was to evaluate serum concentrations of visfatin in patients with subclinical thyroid dysfunction before and after normalization of thyroid function tests. The study included 43 patients (mean age 50.1 ± 10.6 years) with subclinical hypothyroidism. Serum insulin, visfatin, TSH, free T4 (FT4) and free T3 (FT3) levels of subjects were analyzed. Visfatin levels were measured in all patients before starting therapy and after normalization of thyroid function. Serum visfatin levels of subclinical hypothyroid patients were 0.99 ± 0.45 and they were similar after normalization of thyroid function (p = 0.394). Serum visfatin levels were negatively correlated with FT4 levels before treatment (r = ?0.329 p < 0.05). There was no significant correlation between serum levels of visfatin and the serum levels of TSH and FT3. Serum visfatin levels did not correlate with insulin, fasting blood glucose, total cholesterol, HDL cholesterol, LDL cholesterol and triglyceride levels. In this study, it was shown visfatin levels did not change after replacement therapy in patients with subclinical hypothyroidism. Subclinical hypothyroid state may be an earlier stage regarding the changes of adipocytokines specifically the visfatin secretion as seen in overt hypothyroidism.     

3,5-diiodo-L-thyronine increases resting metabolic rate and reduces body weight without undesirable side effects

Recently, it was demonstrated that 3,5-diiodo-L-thyronine (T2) stimulates the resting metabolic rate (RMR), and reduces body-weight gain of rats receiving a high-fat diet. The aim of this study is to examine the effects of chronic T2 administration on basal metabolic rate and body weight in humans. Two euthyroid subjects volunteered to undergo T2 administration. Body weight, body mass index, blood pressure, heart rate, electrocardiogram, thyroid and liver ultrasonography, glycemia, total cholesterol, triglycerides, free T3 (FT3), free T4 (FT4), T2, thyroid stimulating hormone (TSH) and RMR were evaluated at baseline and at the end of treatment. RMR increased significantly in each subject. After continuing the T2 treatment for a further 3 weeks (at 300 mcg/day), body weight was reduced significantly (p<0.05) (about 4 percent), while the serum levels of FT3, FT4 and TSH, were unchanged. No side effects were observed at the cardiac level in either subject. No significant change was observed in the same subjects taking placebo.     

甲状腺癌术后短期甲状腺功能低下对骨代谢的影响

目的:观察分化型甲状腺癌(DTC)患者手术后、碘131(131I)清甲治疗前停用甲状腺素造成的短期甲减对骨代谢的影响。方法:选择DTC术后患者53例作为试验组,50例健康人作为对照组,试验组于停服甲状腺素第二天空腹采血行游离甲状腺素(FT4)、游离三碘甲状腺原氨酸(FT3)、促甲状腺激素(TSH)、血钙(Ca)、血磷(P)、血清碱性磷酸酶(ALP)、血清骨钙素(BGP),I型前胶原羧基末端前肽(PICP)、I型胶原交联羧基末端肽(ICTP)等各项检查,停服甲状腺素4周后于131I治疗前再行上述检查,对照组于体检当日采空腹血测相同项目。结果:试验组患者停药前血清FT3、FT4水平明显高于对照组,差异有统计学意义(P0.05)。停服甲状腺素后,试验组患者血清TSH升高,T3、T4水平降低,血BGP、血Ca、PICP、ICTP水平降低,与停药前及对照组的检验结果相比均有明显差异(P0.05)。停药后,骨密度与停药前比较差异无统计学意义(P0.05)。停服甲状腺素前后血磷水平无明显变化,与对照组相比也没有明显差异(P0.05)。结论:甲状腺癌术后造成甲状腺功能低下可明显影响患者骨代谢,应于131I后及时给予甲状腺激素,及时纠正甲低状态,同时也可适量补充钙剂。     

Central hypogonadism in burned men

Serum samples were obtained from 30 burned men at different times up to the fourth month after injury. Mean concentrations of estradiol (E2) were elevated above those for healthy control subjects. Mean serum total testosterone (T), sex hormone-binding globulin (SHBG), bioassayable luteinizing hormone (LH), thyroxine (T4), triiodothyronine (T3) and their free indices (FT4I and FT3I) were depressed below those of controls during the first postburn week. Mean values for T and LH were progressively higher in samples taken from later time periods but remained depressed. Mean SHBG and thyroid hormones rose and were not significantly different from control values during later periods of the study. Calculated non-SHBG-bound T (NSBT) was below normal in each time period. The close correlation of SHBG values with those of T3 and FT3I in the patients suggests that SHBG responds to the altered thyroid hormone milieu of burn injury. It is postulated that elevated serum E2 perhaps from adrenal precursors promotes an alteration of hypothalamic function resulting in a markedly reduced secretion of bioactive LH and diminished Leydig cell function.     

Influence of experimental acidosis on the concentrations of thyreostimulin (TSH) and iodothyronines (total T4, free T4, T3) in the plasma of the newborn lamb

The effects of acute acidosis on neonatal thyroid function were studied by infusing HCl for 4 h in 42 to 54-h-old lambs. Animals of the same age, used as controls, were simultaneously infused with physiological saline. HCl infusion induced a sharp decrease in blood pH and total restoration did not occur before 48 h. When compared to control lambs, this experimental acidosis was associated with slight, but significant, decreases in plasma TSH, total T4, free T4 and total T3 levels, and in values of the free T4/total T4 ratio; the T3/FT4 ratio was not affected. The values of RT3/FT4 ratio were significantly increased in acidotic lambs. It is concluded that acidosis induced only modest secretory changes in neonatal thyroid function and slightly reduced the proportion and the amount of free T4.     

Decreased free fraction of thyroid hormones after prolonged Antarctic residence

We investigated the effects of Antarctic residence (AR) on serum thyroid hormone and cardiovascular responses to a 60-min standard cold air (0 degree C) test (SCAT). Serum total thyroxine (TT4) and serum total triiodothyronine (TT3), free T4 (FT4) and T3 (FT3), thyrotropin (TSH), and percent free fraction of T4 (%FT4) and T3 (%FT3) were measured in normal men (n = 15) before and after each of three SCATs. The SCAT was first carried out in California and then repeated after 24 and 44 wk AR. Mean arterial pressure (MAP) and sublingual oral temperature (Tor) were measured before and during each SCAT. The SCAT did not alter thyroid hormones before or after AR. The %FT4 decreased from 0.0334 +/- 0.0017 to 0.0295 +/- 0.0007% (P less than 0.002) with 44 wk AR but without a significant change in TT4 or FT4 for the same period. The %FT3 also decreased from 0.2812 +/- 0.0128 to 0.2458 +/- 0.0067% (P less than 0.005) after 44 wk AR. FT3 decreased (P less than 0.003) but TT3 and TSH were unchanged with 44 wk AR. The decrease in %FT4 and %FT3 may be theoretically accounted for by a 10% increase in either the capacity or the affinity of the serum binding proteins. The SCAT in California increased MAP and did not change Tor. After 44 wk AR, the SCAT no longer increased MAP but did lower Tor. The shift in the Tor and MAP response to the SCAT is consistent with the associated occurrence of cold adaptation during AR. We describe for the first time a decrease in the free fraction of both serum T3 and T4 present with extended polar residence and independent of a SCAT, further characterizing the recently reported "polar T3 syndrome."     

Enhanced chemiluminescence in the measurement of proteins and haptens: Evaluation of choriogonadotropin (hCG) and free thyroxin

We evaluated the Amerlite system (Amersham, Bucks, UK) for hCG and FT4. The within-run imprecision (CV%) for hCG was 4.05 at 19.6 U/I (n = 10), 6.28 at 43.45 U/I (n = 10) and 4.62 at 298.57 U/I (n = 10). The between-run imprecision (five replicates for ten days) was 4.8%, 15% and 11%, respectively. The system was linear up to 200 U/I. A good correlation between Amerlite hCG and an IRMA assay (Becton Dickinson, r = 0.91), Delfia (Pharmacia, r = 0.91) and an automated ELISA assay on ES 600 (Boehringer, r = 0.92) was observed on 70 samples. Within-run imprecision for FT4 was 3.8% at 0.7 ng/dl (n = 10), 3.3% at 1 ng/dl (n = 10) and 4.32% at 5.15 ng/dl (n = 10), and between-run was 5.95%, 4.4% and 8.2%, respectively. The comparison with a commercial direct RIA (Becton Dickinson) showed good correlation (r = 0.90, n = 100 samples). The diagnostic value of the association of thyrotropin and FT4, in comparison with the traditional thyroid tests (T3, T4, thyrotropin, FT4, FT3) has been assessed in various thyroid diseases.     

131I对男性甲状腺功能亢进症血清性激素及甲状腺球蛋白水平影响研究

目的:探讨~(131)I对男性甲状腺功能亢进症患者血清性激素及甲状腺球蛋白水平的影响。方法:收集我院收治的男性甲状腺功能亢进症患者74例,随机分为对照组和实验组,每组各37例,对照组患者给予他巴唑口服,20-30 mg/次,每日口服1次。实验组患者在对照组基础上给予~(131)I治疗。治疗结束后,检测并比较两组患者血清游离三碘甲状腺素(FT3)、游离甲状腺素(FT4)、促甲状腺激素(TSH)、睾酮(T)、雌二醇(E2)、甲状腺球蛋白(TG)水平的变化以及临床疗效。结果:与治疗前相比,两组患者血清FT3、FT4、T、E2、TG水平均显著下降,TSH水平明显升高(P0.05);与对照组相比,实验组患者血清FT3、FT4、T、E2、TG水平较低,TSH水平以及临床治疗有效率较高(P0.05)。结论:~(131)I能够显著降低男性甲状腺功能亢进症血清FT3、FT4、T、E2、TG水平,升高TSH水平,临床效果较好。     

甲功五项化学发光免疫分析的基质效应对临床测值的影响

目的:探索评价基质效应在化学发光免疫分析中对甲状腺功能五项指标的影响。方法:选取甲状腺功能五项高值血清,用10种基质牛血清、马血清、山羊血清、水解明胶、BSA、PBS、生理盐水、正常人血清、甲减人血清、甲亢人血清分别对T3、T4、FT3、FT4、TSH的高值血清进行倍比稀释,观察基质效应,另将10种基质用考马斯亮兰法检测蛋白含量,分析蛋白含量与基质效应的关系。结果:T3项目牛血清、水解明胶、BSA有明显基质效应;T4和FT3项目牛血清、水解明胶、BSA、PBS、生理盐水有明显基质效应;FT4项目牛血清、马血清、水解明胶、BSA、PBS、生理盐水有明显基质效应;TSH项目没有发现基质效应,正常人血清、甲减人血清和甲亢人血清对甲状腺功能五项无基质效应。检测结果显示蛋白含量多少与基质效应无关。结论:人血清基质是用于稀释样本,基质效应最小的液体,针对个体差异性进行的选择,稀释T3、T4、FT3、FT4高值血清选择甲减人血清,稀释TSH高值血清选择甲亢人血清,可以得到较为满意的结果。     

Clinical evaluation of accuracy in determining serum free thyroxine and free triiodothyronine in patients with non-thyroidal illness: immunoglobulin effect on T3/TBG ratio and T4/TBG ratio

We examined the effect of endogenous immunoglobulins (G, A and M) and albumin on the measurement of thyroid hormones by different methods, including a new non-isotopic immunoassay of free thyroxine (FT4) and free triiodothyronine (FT3), in a large number of patients with non-thyroidal illness (NTI). Variations in serum protein concentrations can affect the results of radioimmunoassay of human thyroid hormones and thyroxine binding globulin (TBG). Our data revealed that in patients with non-thyroidal illness, when fluctuations in serum gamma-globulin occurred the T3/TBG and T4/TBG ratios altered. Consequently, when patients are suffering from non-thyroidal illness with changing gamma-globulin levels, clinical scientists should take care when they use T3/TBG and T4/TBG ratios as a substitute for FT3 or FT4 estimation. We found FT4 and FT3 (determined with Amerlex-M kits) T3 and the T3/TBG ratio were altered inversely due to the difference in the serum gamma-globulin levels. A recently developed enhanced luminescence enzyme immunoassay for FT3 and FT4 (Amerlite FT3 and FT4 kits) provides more reliable and accurate results, because of its resistance to interference, especially from albumin and gamma-globulin.     

Serum levels of the cytokines IL-1beta, IL-6 and ICAM-1 after 131I-treatment of Graves' disease and nodular goiter.

Cytokines might be involved in the immunological flare up, seen in some patients after 131I-treatment. Therefore, we measured serum levels of interleukin-6 (IL-6), interleukin-1beta (IL-1beta), interleukin-6 soluble receptor (IL-6sR) and Intercellular-adhesion-molecule-1 (ICAM-1) as well as tumor necrosis factor (TNF-alpha) after 131I-treatment of Graves' disease and nodular goiter. Seven patients with Graves' disease, eight with toxic nodular goiter and seven with non-toxic nodular goiter, were followed after 131I-treatment. The patients were treated in the euthyroid state. Blood samples were drawn at day 0, 4, 7, 21 and after 3 months. Significant increases were seen in free T4 index (FT4I), free T3 index (FT3I) and thyroglobulin (Tg) within the first weeks, and TSH simultaneously decreased. None of the cytokines demonstrated any change during follow-up, neither in the entire group nor in subgroups. FT4I and FT3I correlated significantly to ICAM-1. In conclusion, our data suggest that there does not seem to be prolonged cytokine activation after 131I-treatment for thyroid disorders.     

Plasma free fatty acids, inhibitor of extrathyroidal conversion of T4 to T3 and thyroid hormone binding inhibitor in patients with various nonthyroidal illnesses.

In order to clarify the role of free fatty acid (FFA) in thyroid hormone abnormalities in patients with nonthyroidal illness, thyroid function, FFA, inhibitor of extrathyroidal conversion of T4 to T3 (IEC) and thyroid hormone binding inhibitor (THBI) were studied in 99 patients with various nonthyroidal illnesses including diabetes mellitus (DM) (n = 35), liver cirrhosis (LC) (n = 33), chronic obstructive pulmonary disease (COPD) (n = 17) and chronic heart failure (CHF) (n = 14). Patients were divided into three groups based on the level of serum T3: Group I (T3 < 50 ng/dl), Group II (50 < or = T3 < 80) and Group III (80 < or = T3). Serum T4, FT3 and the T3/T4 ratio decreased significantly in the order Group III, Group II and Group I (Group III > II > I). The plasma FFA level was 0.91 +/- 0.12 mmol/l in Group I (P < 0.05, vs. Group III), 0.65 +/- 0.06 in Group II and 0.54 +/- 0.04 in Group III, respectively. The incidence of positive IEC was 80.0% in Group I (P < 0.05, vs. Group III), 53.7% in Group II (P < 0.05, vs. Group III) and 34.2% in Group III. However, IEC was not correlated with the serum T3 concentration. The incidence of positive THBI was 80% in Group I (P < 0.05, vs. Group III), 68.3% in Group II and 47.4% in Group III, but THBI was not correlated with the serum T4 level. Positive correlations were observed among FFA, IEC and THBI (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

甲亢患者甲状腺激素水平与血脂代谢相关性分析及临床意义探讨

目的:探讨甲亢患者甲状腺激素水平与血脂代谢指标之间的关系。方法:对160例甲亢患者治疗前后的甲状腺激素(TH)水平、血脂水平进行对照分析。结果:甲亢治疗前后与健康对照组比较,游离三碘甲状腺原氨酸(FT3)、游离甲状腺素(FT4)明显增高,促甲状腺激素(TSH)明显降低,差异有统计学意义(P<0.01);总胆固醇(TC)、三酰甘油(TG)、高密度脂蛋白胆固醇(LDL-C)、载脂蛋白A(apoAΙ)、载脂蛋白B(apoB)均明显降低,且差异具有统计学意义(P<0.01);低密度脂蛋白胆固醇(HDL-C)无明显变化(P>0.05)。结论:甲状腺激素与脂类代谢密切相关,临床上在诊治甲亢患者时,应当加强血脂水平的监测,以便更好地指导临床诊治,为疾病的发生发展、判断预后提供有价值的实验室检测指标。     

A case of hypothyroidism with simultaneous presence of stimulating type anti-thyrotropin (TSH) receptor antibodies and anti-thyroxine (T4) autoantibodies.

We have examined a hypothyroid patient with stimulating type anti-thyrotropin (TSH) receptor antibodies and without blocking type anti-TSH receptor antibodies. Although she had high serum TSH (240 microU/ml) and low free triiodothyronine (FT3, 0.49 pg/ml) concentrations, which agree with physical findings of hypothyroidism, she had an unusually high free thyroxine (FT4) concentration (3.56 ng/dl). Incubation of her serum with 125I-T4, followed by precipitation with 12.5% polyethylene glycol (PEG) disclosed a higher binding of 125I-T4 (34.4%) than in normal controls, being 5-7%. In addition, binding of 125I-T4 to her serum gamma-globulin was completely displaced by the addition of unlabelled T4. From these results it was concluded that her serum contained anti-T4 autoantibodies. Treatment with synthetic T4 was begun and her thyroid function was monitored by sensitive TSH radioimmunoassay (RIA) and RIA of FT4 after PEG treatment. Since both sensitive TSH RIA and FT4 RIA results after PEG treatment give results concordant with the physical findings, it was concluded that both of the RIA results are useful for the evaluation of thyroid function in patients with thyroid hormone autoantibodies.     

Thyroid hormone levels during a 3-week professional road cycling competition

AIMS: The aim of this investigation was to examine the thyroid hormone levels of professional cyclists during a 3-week stage competition (Vuelta a Espa?a 1998). METHODS: The study population was made up of 16 male cyclists from two world-leading professional teams. Four blood samples were drawn (between 07:00 and 09:00 a.m.) from each participant before and at the end of the 1st, 2nd and 3rd weeks of competition. 3,5,3'(-Triiodothyronine (T(3)), free T(3) (FT(3)), thyroxine (T(4)), free T(4) (FT(4)) and thyroid-stimulating hormone (TSH) were determined in each blood sample by radioimmunoassay. RESULTS: Serum T(4), FT(4) and FT(3) levels showed a significant increase (p < 0.05) by the last week of competition while concentrations of TSH and T(3) remained unchanged. CONCLUSION: In conclusion, 3 weeks of competition provokes changes in basal thyroid hormone concentrations in professional road cyclists.