TBG-dependency of age related variations of thyroxine and triiodothyronine.

Thyroxine (T4), triiodothyronine (T3) and thyroxine-binding globulin (TBG) were determined in healthy individuals ranging in age from newborn to 95 years. T4: 10.25 +/- 1.62 microng/100 ml, T3: 1.62 +/- 0.35 ng/ml and TBG: 1.34 +/- 0.15 mg/100 ml, were found elevated until puberty compared to a middle age group with T4: 7.27 +/- 2.26 microng/100 ml, T3: 1.15 +/- 0.24 ng/ml and TBG: 0.98 +/- 14 mg/100 ml. T4 and T3 followed almost TBG concentration. In old age is dissociation between T4: 5.79 +/- 1.56 microng/100 ml, T3: 0.79 +/- 0.21 ng/ml and TBG: 1.28 +/- 0.15 mg/100 ml was found. Except for old age the ratio T4/TBG and T3/TBG minimized the age dependent variation of T4 and T3 and reduced the coefficient of variance from 26% to 17.7% for T4 and from 26.5 to 25% for T3. Age reduction of T4/TBG is 15% and of T3/TBG 13% respectively more pronounced than for T4 and T3 alone. These data indicate: 1) age related variations of T4 and T3 due to age dependency of TBG, 2) deviation of T4 and T3 values in old age from that expected by their TBG levels and 3) the importance of the routine use of hormone/TBG ratio.     

Response of thyrotropin, prolactin and free thyroid hormones to graded exercise in normal male subjects

Serum levels of thyrotrophin (TSH), prolactin (PRL), free thyroxine (FT4) and free triiodothyronine (FT3) were determined before and after physical exercise in 21 normal male subjects. The subjects were divided into 3 groups as follows: group I--light exercise (exercise on the Mijnhardt bicycle ergometer at 100 Watts for 15 min); group II--moderate exercise (a 5 km marathon); group III--heavy exercise (a 10 km marathon). In group I, TSH level rose from 1.96 +/- 0.42 mu u/ml (mean +/- SEM) to 2.52 +/- 0.30 mu u/ml (p less than 0.01), and PRL levels rose from 11.0 +/- 2.0 ng/ml to 19.0 +/- 5.2 ng/ml (p less than 0.01). In group II, TSH rose from 2.11 +/- 0.51 mu u/ml to 2.62 +/- 0.56 mu u/ml (p less than 0.05), and PRL rose from 11.2 +/- 1.6 ng/ml to 24.0 +/- 5.2 ng/ml (p less than 0.01). In group III, TSH rose from 2.01 +/- 0.41 mu u/ml to 2.36 +/- 0.45 mu u/ml (p less than 0.02), and PRL rose from 12.1 +/- 2.0 ng/ml to 47.7 +/- 9.3 ng/ml (p less than 0.01). The serum levels of FT4 showed different results among the three groups: Group I showed an increased response from 1.60 +/- 0.12 ng/dl to 1.72 +/- 0.12 ng/dl (p less than 0.01); Group II showed no significant difference; and group III demonstrated a diminished response from 1.61 +/- 0.14 ng/dl to 1.45 +/- 0.16 ng/dl (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum thyroid hormones and reproductive characteristics of Rambouillet ewe lambs treated with propylthiouracil before puberty

Twenty-four Rambouillet ewe lambs (average weight=43.7+/-1.2 kg, approximately 6 months of age) were used to examine the effect of thyroid suppression before the onset of puberty on serum thyroid hormones, body weights (BW), and reproductive performance. Beginning in early September, ewe lambs were randomly assigned to three treatments (n=8 lambs/treatment). All animals remained in a single pen (4 x 12 m) with access to salt, water, shade and alfalfa hay (2.5 kg per animal per day) throughout the experiment. Beginning on Day 0 (first day of treatment), all ewe lambs received daily treatments (gavage) for 15 days consisting of 0, 20, or 40 mg 6-N-propyl-2-thiouracil(PTU)/kg BW per day. Beginning on Day 15, the 20 and 40 mg treatments were lowered to 10 and 20 mg PTU/kg BW, respectively. All animals were treated for 28 days. Ovarian cyclicity was determined by twice weekly progesterone (P(4)) analysis. Thyroxine (T(4)) concentrations were similar on Day 0 (61.6, 54.8 and 56.9+/-2.5 ng/ml, P=0.17) in ewe lambs receiving 0, 20 and 40 mg PTU/kg BW, respectively. By Day 7, both PTU-treated groups had T(4) values less than 20 ng/ml (9.0 and 15.4+/-2.5 ng/ml) compared with 78.5 ng/ml in controls (P<0.01). By 7 days after termination of PTU treatment, serum T(4) had risen to 29.1 and 26.9 (+/-2.9)ng/ml in the 20/10 and 40/20 PTU groups, respectively. On Day 66, control ewes had 55.0 ng T(4)/ml compared with 43.1 and 39.0 (+/-2.6 ng/ml) for ewes in the 20/10 and 40/20 groups, respectively (linear, P<0.01). Serum triiodothyronine (T(3)) followed a similar pattern to that observed for T(4). Ewe lamb BW were similar (P>0.50) among groups throughout the treatment period. However, following the treatment, PTU-treated ewes tended (P<0.10) to weigh less than controls. Average Julian day of puberty was also similar (P>0.50) among treatments (286, 288 and 288+/-5 days; control, 20/10 and 40/20, respectively). Control ewes had a pregnancy rate of 75%, while both PTU-treated groups had pregnancy rates of 88% (P>0.20). The administration of PTU resulted in a rapid decline in serum T(4) and T(3) but neither time of puberty nor pregnancy rates were affected by lowered thyroid hormones.     

Effects of exogenous TSH on the thyroid activity of adult or neotenic amphibians

In adult Anuran and neotenic Urodela, bred in laboratory conditions, the levels of plasma thyroid hormones are undetectable (T3 less than 50 ng/100 ml, T4 less than 5 ng/100 ml). Thyroid function can be reactivated after ovine TSH treatment. Under those conditions, metamorphosis is induced in the axolotl and T4 plasmatic levels reaches 0,53 +/- 0,13 micrograms/100 ml and those of T3 9 +/- 2,64 ng/100 ml. In adult Anuran, thyroid reactivation under thyrotropic treatment determines an increased secretion of T4 whereas T3 remains below the limits of detection of the assay procedure. This aptitude of adult Anuran thyroid to answer thyrotropic stimulation suggests a cyclic function of the gland after metamorphosis.     

Serum T3 level in the patients with hyperthyroidism after therapy.

Serum T3 level in various thyroid diseases was determined in unextracted serum with the Dainabot kit for T3 RIA. The serum T3 level in 33 normal subjects was 0.8-1.6 ng/ml. It was 5.7 +/- 3.5 ng/ml (mean +/- S.D.) in 36 hyperthyroid patients, and undetectable to 0.8 ng/ml in 21 hypothyroid patients. Generally the serum T4 and serum T3 decreased in parallel after radioiodine therapy for hyperthyroidism. However, in some cases the serum T3 level remained high in spite of normalized serum T4 after radioiodine therapy. This state indicated "T3-toxicosis", and hyperthyroidism was apt to recur. When thyroid function was observed for 2 years following radioiodine treatment, the ratio of serum T3 (T3 level before treatment/T3 level after treatment) decreased more significantly as compared with the ratio of serum T4 in euthyroid cases. Serum T3 provides a more sensitive index of thyroid function than serum T4 in euthyroid states after radioiodine or anti-thyroid drug therapy. The present data indicate that the serum T3 level and the T4/T3 ratio are valuable aids in the estimation of prognosis of hyperthyroid patients after various treatments.     

Serum thyrotropin response to thyrotropin-releasing hormone and free thyroid hormone indices in patients with familial thyroxine-binding globulin deficiency.

The response in serum thyrotropin (TSH) to synthetic thyrotropin-releasing hormone (TRH) as well as serum free thyroxine index (FT4I) and free triiodothyronine index (FT3I) was investigated in six patients with familial thyroxine-binding-globulin (TBG) deficiency. The total serum thyroxine (T4) and triiodothyronine (T3) concentrations were significantly decreased, compared with those of normal subjects (3.4 +/- 0.9 microgram/dl, mean +/- SD. vs. 9.0 +/- 1.5 microgram/dl, p less than 0.01 and 87 +/- 27 ng/dl vs. 153 +/- 37 ng/dl, p less than 0.01, respectively). FT4I was lower than the normal range in all but one (5.3 +/- 1.5 vs. 8.9 +/- 1.6, p less than 0.01), whereas FT3I was all in the normal range and of no significant difference from the normal control (132 +/- 22 vs. 148 +/- 25). Serum TSH concentrations in TBG deficiency were all in the normal range (1.0-4.2 muU/ml) and the maximum TSH increments following TRH 500 microgram iv were 8.9 +/- 2.0 muU/ml and of no significant difference from the normal control (10.2 +/- 4.5 muU/ml). These results indicate that the euthyroid state in familial TBG deficiency is more clearly defined by TRH-test and the normal response to TRH in familial TBG deficiency is presumably under the control of the serum free T3 level rather than the serum free T4 level.     

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。     

Serum thyroid hormones and performance of offspring in ewes receiving propylthiouracil with or without melatonin

Two experiments were conducted during mid-gestation to examine effects in ewes of propylthiouracil (PTU) treatment alone or with melatonin on serum thyroid hormones, postpartum reproduction, and lamb performance. In the first experiment, beginning on day 0 (first day of treatment when all animals were 72.2+/-0.9 days of gestation), ewes received daily treatments (gavage) consisting of either 0mg (n=6) or 40 mg (n=6) PTU/kg body weight/day for 15 days. After 15 days, the 40 mg dosage was decreased to 20mg/kg body weight for an additional 20 days (35 days of PTU). Serum thyroxine (T4) did not differ (P>0.10) between groups through day 4; but on day 5, control females had a serum value of 67 ng/ml compared with 46 (+/-5)ng/ml for PTU-treated ewes (P=0.02). On the last day that 40 mg of PTU was administered, serum T4 averaged 67 and 7 (+/-5)ng/ml (P<0.001) in the two respective groups. Serum T4 remained low and was 80 and 1 ng/ml (P<0.001) in control and treated ewes on day 34. Serum T4 rose gradually after PTU but remained different from that observed in control ewes through day 48. Lambs from control and treated ewes had similar (P=0.46) T4 values at birth but lambs from PTU-treated ewes had lower (P=0.03) birth weights than did those from control ewes. Serum progesterone (P4) after parturition indicated a lack of cyclicity in all ewes. In the second experiment, beginning on day 0 (76.8+/-4.7 days of gestation), ewes received PTU as in Experiment 1. In addition, after 15 days of PTU, melatonin was given (i.m. injections at 5mg/day) for 30 days. Propylthiouracil decreased (P0.60) for lambs born to control and treated ewes. Female offspring of PTU+melatonin-treated dams reached puberty, became anestrus, and returned to cyclicity at similar (P>0.10) times to contemporary ewe lambs. Results indicate that 40/20mg PTU alone or with melatonin does not induce cyclicity after lambing in spring lambing ewes and has little effect on offspring performance.     

Destructive thyrotoxicosis in a patient with anaplastic thyroid cancer

A 55-year-old man was admitted to our hospital with an anterior neck tumor, hoarseness, and dysphagia that had continued for a few weeks. He was diagnosed as anaplastic thyroid cancer by fine-needle aspiration cytology. He was treated by external radiation and chemotherapy, but left hemothorax developed and he died of respiratory failure on the 76th day in hospital. On admission, the levels of serum free triiodothyronine (FT3), free thyroxine (FT4), and TSH were 12.8 pg/ml, 4.2 ng/dl, and 0 microU/ml, respectively. The simultaneous thyroidal I-131 uptake rate was 1.2% at 24 hours. The levels of free thyroid hormones fell gradually without antithyroid drugs to result in hypothyroidism (FT3 0.8 pg/ml, FT4 0 ng/dl, and TSH 36 microU/ml). The rapid growth of anaplastic thyroid cancer seemed to be responsible for destructive thyrotoxicosis followed by hypothyroidism in this patient.     

Thyroid hormone action on ACTH secretion

Thyroid hormone effects on pituitary ACTH have not been well established. Adult male Sprague-Dawley rats were rendered hypo- and hyperthyroid while undergoing treatment with 6-Propylthiouracil (PTU) and L-Thyroxine (T4). At the time of decapitation, plasma values for T4 (micrograms/100 ml) were 3.9 +/- 0.4 in the control, 17.3 +/- 2.2 in the T4 and less than 2 in the PTU treated group; plasma T3 and TSH confirmed hyper- and hypothyroidism in the T4 and PTU treated groups respectively. Plasma immunoassayable ACTH and corticosterone were significantly increased in hyperthyroid and decreased in the PTU treated animals. Pituitaries were removed and incubated in DMEM. After 3 h incubation, ACTH content and secretion to the medium were significantly lower in the PTU group. As expected, pituitary TSH content and secretion were decreased in the T4 treated animals. These data indicate that thyroid hormones influence pituitary-adrenal function by increasing ACTH secretion and consequently corticosterone production.     

Congenital goiter sustaining normal level of serum triiodothyronine

We attempted to elucidate the deficient site of thyroid hormone biosynthesis in the thyroid gland and the mechanism of sustaining normal T3 level in sera of a patient with congenital goiter. TY, a 8-yr-old boy, first noted the onset of a diffuse goiter at the age of 2. There was no clinical evidence of hypothyroidism except for the slight impairment of intellectual development and the awkward physical activity. BMR, T3-RSU and T4 showed low values (-13%, 20.8% and 2.2 micrograms/dl), but serum T3 was normal (180 ng/dl). Serum TSH was 18 microU/ml. The intrathyroidal T3 and T4 were slightly low. Thyroidal 131I uptake was high, but KSCN discharge test was negative. Percent distribution of 131I labelled amino acids in the pancreatin digested thyroid homogenate was 17.4% in MIT, 33.4% in DIT and 11.3% in T3 and T4. Thyroid iodide peroxidase activities in mitochondrial and microsomal fractions were slightly low (19.6 and 26.8 (normal: 32 +/- 3.0 and 37.4 +/- 9.5) mumoles/mg protein). The activity was not increased by the addition of hematin. Thyroglobulin was found to be normal. A biological half life of 131I labelled T4 was shorter (3.5 days) than that of the normal. Electron microscopic examination exhibited the increment and expansion of endoplasmic reticulum in the follicular cell. Low iodide peroxidase activity of this patient may correlate to low T3 and T4 level in the thyroid cell. Moreover, shortened biological half life of T4 implies that normal T3 level in serum is sustained by the accelerated conversion of T4 to T3 in peripheral tissues.(ABSTRACT TRUNCATED AT 250 WORDS)     

Negative effect of iodide on the survival of newly divided epithelial cells in chronically stimulated rat thyroid

The aim of this work was to investigate some aspects of the thyroid epithelial cell kinetics during the iodide-induced involution of a hyperplastic goitre in the rat. Rats were made iodine-deficient for 6 months, and propylthiouracil (PTU) (0.15%) was added to the diet during the last 2 months. Thereafter, rats were refed with iodide and PTU was removed (day 0). Forty-eight hours previously, all the rats were injected with tritiated thymidine ([3H]TdR) (1 microCi/g). Some animals were killed 1 hr or 24 hr after [3H]TdR injection (i.e. on day -2 and -1, day 0 corresponding to the restoration of a normal iodine diet); the other animals were killed after different delay periods and following [3H]TdR injection. Autoradiography of thyroid sections, iodine determination of plasma iodide and protein-bound iodine (PBI), and RIA of plasma thyroid stimulatory hormone (TSH) were performed. Plasma TSH concentration was very high on day 0 of iodide refeeding (3000 +/- 330 ng/ml) and remained at this level until day 8. Plasma PBI was very low on day 0, remained so until day 4 and greatly increased on day 8. Plasma iodide was also very low on day 0, but markedly increased on day 1, then did not vary significantly until day 43 of iodine refeeding. Thyroid weight, elevated on day 0, decreased relatively quickly until day 30, then more slowly until day 73. The [3H]TdR labelling index (LI) of the thyroid epithelial cells (TEC) was high on day 0 (56 +/- 3 labelled cells/10,000 cells), and 24 hr thereafter increased to 104 +/- 3, by division of the labelled cells. On day 1 of iodine refeeding, the LI had abruptly decreased to about half this value and then remained stable for 3 more days. Between day 4 and day 16, a progressive decline in the LI, (by about 3-4 per day), was observed. The LI showed no further modification, up to day 73, the longest period investigated. The decrease in LI occurred without any significant changes in the labelling intensity (grain count) of the remaining labelled cells between day 1 and 16, this indicates that no cell division took place during this period. The data are therefore interpreted as showing a biphasic elimination after iodide refeeding, of cells that were actively proliferating during the goitrous state.(ABSTRACT TRUNCATED AT 400 WORDS)     

Soluble tumour necrosis factor-alpha receptor I and interleukin-6 as markers of activity in thyrotoxic Graves' disease.

Autoimmune thyroid diseases are thought to be mediated by pro-inflammatory cytokines such as TNFalpha and IL-6. Serum levels of cytokines may indicate activity levels of immune functions. We investigated serum levels of IL-6 and of the soluble receptor of TNFalpha in patients with newly diagnosed onset of Graves' hyperthyroidism. The predominantly female group consisted of 39 patients, mean fT4 was 47.6 pg/ml (normal values 7.5=19.0 pg/ml). After diagnosis, all patients were treated with anti-thyroid drugs. Soluble Tumour Necrosis Factor Receptor I (TNF-RI) serum levels were found significantly increased (mean 3.7+/-1.3 ng/ml; p<0,01) compared to a matched group of apparent healthy individuals (mean sTNF-RI 1.8+/-0.5 ng/ml) and to a matched group of patients with treated Graves' disease (mean sTNF-RI 1.9+/-0.6 ng/ml). When IL-6 was assessed only 4 of the 39 patients exhibited increased serum levels. Our finding may indicate that sTNF-RI and possibly its ligand, TNFalpha, could play an important role in the onset of the acute stage of Graves' disease.     

Goiter and impairment of thyroid function in acromegalic patients: basal evaluation and follow-up.

AIMS: We evaluated morphological, biochemical and cytological thyroid parameters in acromegalic patients, investigated before and after treatment for acromegaly. PATIENTS: 28 acromegalics were investigated before and, in 18 cases, after 2-7 years of therapy. Fourteen patients were from areas of moderate iodine deficiency in Southern Italy. One patient underwent thyroidectomy before entering this study. RESULTS: 19 patients were euthyroid (FT4: 17.7 +/- 0.8 pmol/l and FT3 4.6 +/- 0.2 pmol/l), but TSH was undetectable in 5/19. Among them, TRH-stimulated TSH increase was absent/impaired or exaggerated/delayed in 9 and one cases, respectively. Decreased FT3 and/or FT4 values with low/normal TSH values were detected in 7 cases; TRH-stimulated TSH response was absent/impaired in 2 patients and exaggerated/delayed in another two. Increased free T4 and free T3 concentrations with undetectable TSH levels were found in one. Two euthyroid patients had high TPOAb levels. Goiter was diagnosed in 21 cases and nodules were found in 14/21. 99Tc scintiscan showed "cold" areas in 13/14 cases and a "hot" nodule in the hyperthyroid patient. Acromegalics from iodine deficient areas showed a not significant increase of prevalence of goiter (86 vs. 71 %) and of mean thyroid volume (35 +/- 7 vs. 28 +/- 4 ml, NS), compared to others. Thyroid volume (TV) did not correlate with GH, IGF-1 and TSH levels, the area under the curve of insulin-increase during OGTT, the age of patients or the duration of acromegaly. Fine needle aspiration biopsy (FNAB), performed in 11/14 patients with nodular goiter, showed colloid nodules in 8 cases, hyperplastic nodules in 2 and an adenomatous nodule in one. Neurosurgery, radiotherapy or medical treatment for acromegaly induced a significant decrease of mean GH and IGF-1 levels (21.5 +/- 8.5 vs. 12.9 +/- 9.6 ng/ml, p< 0.005 and 747 +/- 94 vs. 503 +/- 88 ng/ml, p < 0.02, respectively), but both GH and IGF-1 values normalized only in 3 cases. No significant variation of mean TSH levels was found. Although TV normalized in 3 patients, ultrasound evaluation showed a not significant decrease of mean TV and no changes in the diameter and number of nodules. FNAB was unchanged. CONCLUSIONS: Our results suggest that, despite no correlation between serum GH and IGF-1 levels and thyroid volume being found, a decrease in serum GH and IGF-1 levels has favourable effects on thyroid status.     

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)     

丙基硫氧嘧啶影响妊娠合并甲状腺功能亢进孕妇甲状腺功能及妊娠结局的研究

目的:探讨丙基硫氧嘧啶(PTU)影响妊娠合并甲状腺功能亢进(甲亢)孕妇甲状腺功能及妊娠结局的影响。方法:选择我院妇产科2010年3月至2013年1月收治的110例妊娠合并甲亢的患者作为观察对象,随机分为观察组58例,对照组52例。观察组予PTU每天300 mg口服,对照组确诊后未能定期检测甲状腺功能而自行停药,或拒绝PTU药物治疗。结果:观察组TT3、TT4、FT3、FT4、TSH水平均显著低于对照组,差异均具有统计学意义(均P0.05);观察组早产或流产、剖宫产、妊娠高血压、心力衰竭、重度子痫明显低于对照组,而足月产明显高于对照组,差异均具有统计学意义(均P0.05);观察组的围生儿发生胎儿窘迫、低体重儿、新生儿甲亢、转入NICU发生率均显著低于对照组,两组比较差异均具有统计学意义(均P0.05)。结论:规范的PTU治疗能很好地改善妊娠合并甲亢患者的孕期甲状腺功能,减低甲亢对孕妇及新生儿的危害,改善妊娠结局,且对新生儿畸形率无显著的影响,是一种相对安全和有效的治疗方法。     

Serum TSH, T4, T3, FT4, FT3, rT3, and TBG in youngsters with non-ketotic insulin-dependent diabetes mellitus

Several parameters of thyroid function were studied in 112 non-ketoacidotic youngsters with insulin-dependent diabetes mellitus (IDDM). Levels of thyroxine (T4), reverse triiodothyronine (rT3), thyroxine-binding globulin (TBG) and T3 were lower than in controls, whereas FT4, and FT3 were normal. T4 levels in IDDM patients were positively related to T3, rT3 and TBG, and inversely related to haemoglobin A1 (HbA1). However, only 4 patients showed biochemical hypothyroidism (T4 less than 5 micrograms/100 ml), whereas their FT4, FT3 and thyroid-stimulating hormone (TSH) levels were normal. Concurrent variations of T3 and rT3 levels were found in IDDM patients; thus, their T3/rT3 ratios were stable or higher than in controls, indicating that peripheral deiodination of T4 is preferentially oriented to production of rT3 only during ketoacidosis. Although changes in thyroid function may reflect the degree of metabolic control of diabetes in a large population, the clinical usefulness of serum thyroid hormone measurements in an individual case still appears to be limited.     

The relation between reduced serum melatonin levels and zinc in rats with induced hypothyroidism

The objective of the study was to explore the changes in melatonin and zinc levels in rats with induced hypothyroidism. Thirty adult male rats used in the study were allocated to three groups with equal numbers. Group 1: General control group which was not subjected to any procedure. Group 2: Sham-hypothyroidism group to which was administered 10 mg kg(-1) intraperitoneal (i.p.) physiologic saline (0.09% NaCl) for 4 weeks. Group 3: Hypothyroidism group which was supplemented with intraperitoneal 10 mg kg(-1) propylthiouracil (PTU) for 4 weeks. Blood samples collected from all animals at the end of the study by decapitation were analysed for serum Total T4 (TT4), Total T3 (TT3), Free T4 (FT4), Free T3 (FT3) (ELISA) as well as for melatonin (RIA) hormones and zinc levels (atomic emission). Comparison of the study groups in terms of thyroid hormones, melatonin and zinc levels showed that TT4, TT3, FT4, FT3, melatonin and zinc levels in group 3 were lower than those in groups 1 and 2 (p < 0.01). These parameters were not different in groups 1 and 2. The results of the study demonstrate that PTU supplementation for 4 weeks results in a significant inhibition in both melatonin and zinc levels. Inhibited melatonin levels may result from the decrease in zinc levels.     

Negative Effect of Iodide On the Survival of Newly Divided Epithelial Cells In Chronically Stimulated Rat Thyroid

Abstract. The aim of this work was to investigate some aspects of the thyroid epithelial cell kinetics during the iodide-induced involution of a hyperplastic goitre in the rat. Rats were made iodine-deficient for 6 months, and propylthiouracil (PTU) (0.15%) was added to the diet during the last 2 months. Thereafter, rats were refed with iodide and PTU was removed (day 0).
Forty-eight hours previously, all the rats were injected with tritiated thymidine ([³H]TdR) (1 μCi/g). Some animals were killed 1 hr or 24 hr after [³H]TdR injection (i.e. on day -2 and -1, day O corresponding to the restoration of a normal iodine diet); the other animals were killed after different delay periods and following L³H]TdR injection. Autoradiography of thyroid sections, iodine determination of plasma iodide and protein-bound iodine (PBI), and RIA of plasma thyroid stimulatory hormone (TSH) were performed. Plasma TSH concentration was very high on day O of iodide refeeding (3000 ± 330 ng/ml) and remained at this level until day 8. Plasma PBI was very low on day O, remained so until day 4 and greatly increased on day 8. Plasma iodide was also very low on day O, but markedly increased on day 1, then did not vary significantly until day 43 of iodine refeeding. Thyroid weight, elevated on day O, decreased relatively quickly until day 30, then more slowly until day 73.     

Short and long term effects of radioiodine and antithyroid drugs on T4 binding proteins, free T4 and T3, during Graves' disease therapy.

Ninety five patients with Graves' disease were studied before and at three months intervals after antithyroid drugs (ATD) (31 cases) or radioiodine (64 cases) therapy until recovery. Before treatment, the T4 maxima binding capacity of TBPA was significantly decreased 253.5 +/- 11.4 mug/100 ml)(mean + se) (control values: 287 +/- 10.4 mug/100 ml) (alpha = 0.04), especially in 53.7% of patients (m = 177 +/- 8 mug/100 ml). The mean of TBG (m = 20.7 +/- 0.9 mug/100 ml) was not different from euthyroid subjects (m = 19.7 +/- 1.7 mug/100 ml) except in 51.2% of patients who had a low TBG (m = 14.3 +/- 1.1 mug/100 ml). An inverse linear correlation was found between TBG-DFT4 (alpha = 0.05) and DF T 3 (alpha = 0.002), TBPA-log DF T4 (alpha = 0.05) but not between TBG and TBPA. The physiological relationship between DFT3, DFT4, TT3, TBG and TBPA was studied in vitro; after adding increased quantities of T4 to a pool of sera collected from eu, hypo or hyperthyroid patients, DFT4, DFT3, FT3 index increased in linear positive relationship with TT4 concentrations, the kinetic of this phenomena was inversely correlated with T4 maximal binding capacity of TBG or TBPA for T4. Addition of T3 to the same sera did not show any effect on the previous parameters. DFT3 depended on the level of T4 in serum more than T3 concentration and was in inverse relationship with the maximal binding capacity of TBG. This data might explain the paradoxal normal or slightly increased values of DFT3 found in T3 thyrotoxicosis. In patients treated with ATD or radioiodine, TBPA but not TBG increased significantly on year after. However, in subjects with an initial very low TGB or TBPA, this phenomenon occurred on the third month after radioiodine or ATD. During the same period, DF T4 and DF T3 were inversely correlated to TBG and TBPA. In conclusion, important changes in T4 binding proteins and free fractions of thyroid hormones were observed in Graves' disease but were corrected by antithyroid therapy. All these data were in good agreement with the normalisation of thyroid function.