Physiological variables of horses after road transport

In order to investigate the effects of short road transport stress on total and free iodothyronines, body weight (BW), rectal temperature and heart rate (HR) changes, 126 healthy stallions were studied in basal conditions, before and after transport. A total of 60 Thoroughbred and 66 crossbred stallions aged 4 to 15 years with previous travelling experience were transported by road in a commercial trailer for a period of about 3 to 4 h (distance under 300 km). Blood samples and functional variables were collected in each horse box, one week before loading and transport in basal conditions (control samples), one week later immediately before loading (pre-samples) and again after transport and unloading (about 3 to 4 h) in each new horse box, within 30 min of their arrival at the breeding stations (post-samples). Compared to the before-transport values, increases in circulating T3, T4 and fT4 levels (P < 0.01) were observed after transport, irrespective of breed, but not for fT3 levels. Lower T4 and fT4 levels were observed in basal II (at 1100 h) (P < 0.01) than in basal I (at 0800 h) conditions and before transport. Thoroughbreds showed higher fT3 (P < 0.05) and fT4 (P < 0.01) levels after transport than crossbred stallions. No significant differences were observed for T3 and T4. Compared to the before-transport values, significant increases in rectal temperature (P < 0.01) and HR (P < 0.05) were observed after transport. No differences were observed between basal I, II and before values for functional variables. Significant correlations between T3 and rectal temperature, BW and HR were found. The results indicate that short road transport induces a preferential release of T3, T4 and fT4 hormones from the thyroid gland in relation to different breed, and an increase in rectal temperature and HR. No significant changes in BW were observed. No differences were observed in relation to different ages. The data obtained suggest that the stallion's thyroid hormones and functional variables may play an important role in assessing the effects of transport stress and a horse's coping strategy.     

Antithyroid autoantibodies in the examined population with iodine prophylaxis after the Chernobyl catastrophe

The aim of the present study was the observation of the frequency of antithyroid autoantibodies in the population in low endemic goitre area after mass iodine prophylaxis after the Chernobyl catastrophe and the estimation of TSH and thyroid hormones secretion in this population. On the basis of the investigations carried out we could conclude that the frequency of antithyroid autoantibodies in the population with confirmed endemic goitre is comparable to the frequency of antithyroid autoantibodies in the healthy population. ATA occurrence in children after iodine prophylaxis could confirm the hypothesis that thyroglobulin immunity is higher after iodine intake. The lower T3 concentration observed in the group with antithyroid autoantibodies suggests that autoantibodies may be involved in the thyroid hormones synthesis or peripheral conversion of thyroid hormones.     

Maternal thyroid hormone trajectories during pregnancy and child behavioral problems

There is ample evidence demonstrating the importance of maternal thyroid hormones, assessed at single trimesters in pregnancy, for child cognition. Less is known, however, about the course of maternal thyroid hormone concentrations during pregnancy in relation to child behavioral development. Child sex might be an important moderator, because there are sex differences in externalizing and internalizing behavioral problems. The current study examined the associations between maternal thyroid hormone trajectories versus thyroid assessments at separate trimesters of pregnancy and child behavioral problems, as well as sex differences in these associations. In 442 pregnant mothers, serum levels of TSH and free T4 (fT4) were measured at 12, 24, and 36 weeks gestation. Both mothers and fathers reported on their children's behavioral problems, between 23 and 60 months of age. Latent growth mixture modeling was used to determine the number of different thyroid hormone trajectories. Three trajectory groups were discerned: 1) highest and non-increasing TSH with lowest fT4 that decreased least of the three trajectories; 2) increasing TSH and decreasing fT4 at intermediate levels; 3) lowest and increasing TSH with highest and decreasing fT4. Children of mothers with the most flattened thyroid hormone trajectories (trajectory 1) showed the most anxiety/depression symptoms. The following trimester-specific associations were found: 1) lower first-trimester fT4 was associated with more child anxiety/depression, 2) higher first-trimester TSH levels were related to more attention problems in boys only. A flattened course of maternal thyroid hormone concentrations during pregnancy was a better predictor of child anxiety/depression than first-trimester fT4 levels.     

Thyroid Functions and Trace Elements in Pediatric Patients with Exogenous Obesity

Obesity is a multifactorial disease developing following impairment of the energy balance. The endocrine system is known to be affected by the condition. Serum thyroid hormones and trace element levels have been shown to be affected in obese children. Changes in serum thyroid hormones may result from alterations occurring in serum trace element levels. The aim of this study was to evaluate whether or not changes in serum thyroid hormone levels in children with exogenous obesity are associated with changes in trace element levels. Eighty-five children diagnosed with exogenous obesity constituted the study group, and 24 age- and sex-matched healthy children made up the control group. Serum thyroid stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), thyroglobulin (TG), selenium (Se), zinc (Zn), copper (Cu), and manganese (Mn) levels in the study group were measured before and at the third and sixth months of treatment, and once only in the control group. Pretreatment fT4 levels in the study group rose significantly by the sixth month (p?=?0.006). Zn levels in the patient group were significantly low compared to the control group (p?=?0.009). Mn and Se levels in the obese children before and at the third and sixth months of treatment were significantly higher than those of the control group (p?=?0.001, p?=?0.001). In conclusion, fT4, Zn, Cu, Mn, and Se levels are significantly affected in children diagnosed with exogenous obesity. The change in serum fT4 levels is not associated with changes in trace element concentrations.     

Cardiovascular autonomic function tests in an African population

Background

Age- and sex-specific reference intervals are an important prerequisite for interpreting thyroid hormone measurements in children. However, only few studies have reported age- and sex-specific pediatric reference values for TSH_basal (TSH), free T3 (fT3), and free T4 (fT4) so far. Reference intervals are known to be method- and population-dependent. The aim of our study was to establish reference intervals for serum TSH, fT3, and fT4 from birth to 18 years and to assess sex differences.

Methods

2,194 thyroid hormone tests obtained from a hospital-based pediatric population were included into our retrospective analysis. Individuals with diagnoses or medications likely to affect thyroid function were primarily excluded, as well as the diagnostic groups, if different from the purely healthy subgroup (n = 414). Age groups were ranging from 1 day to 1 month, 1 – 12 months, and 1 – 5, 6 – 10, 11 – 14, and 15 – 18 years, respectively. Levels of fT3, fT4 and TSH were measured on Advia^® Centaur? automated immunoassay system.

Results

The final sample size for reference data creation was 1,209 for TSH, 1,395 for fT3, and 1,229 for fT4. Median and 2.5/10/25/75/90/97.5 percentiles were calculated for each age group. Males had greater mean fT3 concentrations than females (p < 0.001). No sex-differences were found for TSH and fT4 between age-matched serum samples. Median concentrations of fT3, fT4 and TSH were greatest during the first month of life, followed by a continuous decline with age.

Conclusion

Our results corroborate those of previous studies showing that thyroid hormone levels change markedly during childhood, and that adult reference intervals are not universally applicable to children. Moreover, differences of our reference intervals compared to previous studies were observed, likely caused by different antibody characteristics of various analytical methods, different populations or undefined geographic covariates, e.g. iodine and selenium status.     

Iodine concentration in the blood and urine in children depending on the goiter size

Epidemiological investigations have shown that at the Bia?ystok Province about 30% of children and youth is afflicted with goitre. In this area drinking water is poor in iodine and iodine supply with food is quite unsatisfactory. The purpose of the present work has been to check the behaviour of the serum and urine iodine in children with thyroid goitre. The estimations of I in blood serum were made in 126 children with goitre (I, II, and III, according to the WHO classification) and in 100 healthy children. The method used included buthanol extraction according to Fisher and Morris. The concentration of iodine and its excretion rate in urine were assessed in 119 children with goitre of various advancement, an; in 170 children not affected with goitre, using the method of Fisher and Morris adopted to urine analysis. The authors found the following values for serum protein bound iodine: control group 4.9 microgram/100 ml, at average; 4.3 microgram/100 ml, 3.0 microgram/100 ml, and 2.6 microgram/100 ml in those affected with I, II, and III of the goitre, respectively. The 24 hr urine excretion rate of iodine in healthy children amounted to 66.4 microgram, and 64.2 microgram, 53.6 microgram, and 4o.2 microgram in those with I, II, and III goitre, respectively. The above results indicate a significant decrease of iodine concentration in blood serum and in urine in children with goitre; this decrease has been found to be dependent on the degree of the thyroid gland enlargement. The differences were statistically significant.     

Free thyroxine, cognitive decline and depression in Alzheimer's disease

The role of thyroid function in Alzheimer's disease (AD) has been subject to a number of studies during the last years. We investigated the possible relationship between plasma levels of the biologically active free form of thyroxin (fT4) and cognitive function in 227 outpatients with mild to moderate Alzheimer s disease (AD) in a cross-sectional study design. A significant negative correlation was found between plasma fT4-levels and Mini-Mental state examination (MMSE) score (Spearman Rho = -0.14, p=0.04). When the lowest quartile of fT4-levels (<15.1 pmol/l) was compared to the highest quartile (>19.0 pmol/l), statistically significant lower mean MMSE-scores were seen in the group with the highest fT4-levels (p<0.05, ANOVA). The mean difference between the 1st and the 4th quartile of fT4 was 2.6 MMSE-score points. No correlations were found between plasma total T4-levels, plasma total T3-levels, plasma TSH-levels and the MMSE score (p>0.05). When fT4 quartile groups were compared for depression measured in the Geriatric Depression Score (GDS 15), a slightly higher score was seen in the 1s and 2nd compared to the 3rd and 4th quartile groups without reaching statistical significance (1st quartile of fT4: GDS 5.2 +/- 3.8; 2nd: 5.3 +/- 4.0; 3rd: 4.4 +/- 3.4; 4th: 4.5 +/- 3.8) pointing to a reverse correlation of fT4 levels and depressive mood. This study leads to the conclusion that high levels of plasma fT4 might result in a worsening of cognitive impairment and a positive effect on depressive mood in AD.     

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)     

Seasonal variation in thyroid size in healthy males

Thyroid volume, measured ultrasonically, and serum levels of T4, T3 and TSH were determined every season during one year in 13 healthy males. A mean variation in thyroid volume of approximately 23% between minimum values (15.8 +/- 1.7 ml, summer) and maximum values (19.5 +/- 1.9 ml, winter) was found (P less than 0.01), although no significant differences in the other thyroid variables could be demonstrated. This seasonal variation in thyroid size should be taken into account when goitre frequency, goitrogenic action of drugs, and goitre treatment effects are evaluated.     

Therapy of endemic goitre: controlled study on the effect of iodine and thyroxine

Two kinds of medical treatment of endemic goitre (400 microgram of iodine, n=11, and 150 microgram of L-thyroxine, n=12) were compared in a double blind study with a placebo group (n=12) during a period of 12 months and an observation time of three months after cessation of therapy. The means of the neck circumference and of the estimated thyroid volume decreased significantly during treatment in both groups, whereas no significant difference was observed in the placebo group. The results in both therapy groups did not differ significantly from each other. No side effects or symptoms of hyperthyroidism were observed. During treatment the index of free thyroxine (FT4I) increased significantly in both the iodine and the thyroxine group and delta TSH after TRH decreased significantly. Total triiodothyronine (TT3) did not show significant alterations. Three months after cessation of therapy in the thyroxine treated group the mean FT4I dropped into the range before treatment, whereas it remained slightly elevated in the iodine group. In the thyroxine treated group the mean delta TSH was higher than its value before therapy. After withdrawal of iodine, however, the mean delta TSH remained decreased for three months. The study indicates that 400 micrograms of iodine per day may be at least as effective as a standard dose of 150 micrograms of thyroxine to treat endemic goitre in an iodine deficient area.     

Ultrasonic scan of the thyroid gland during the treatment of endemic goiter with L-thyroxine

Forty three adolescents of both sexes (26 female, 17 male) aged between 16 and 19 years with struma diffusa juvenilis were treated with L-thyroxine for 16 months. Size of the thyroid gland was classified according to WHO. The percentage of stages was the following; Ia-12%, Ib-69%, and II-19%. The patients were given L-thyroxine in a daily dose of 100 micrograms. Patients' compliance and the results of therapy were controlled every 4 months, measuring thyroid gland size with ultrasound scan and determining T3, T4 and TSH in serum. It was found that: 1. L-Thyroxine significantly reduces the volume of thyroid gland with insignificant changes in serum T3, T4, and TSH levels. 2. Ultrasound volumetry of the thyroid gland is a precise morphometric technique, reproducible with high degree of specificity. 3. Monotherapy with L-thyroxine given for at least one year is effective in endemic goitre. The authors discuss also literature on ultrasound volumetry of the thyroid gland and therapies in comparison with own results.     

TSH and prolactin secretions in Hashimoto's thyroiditis following withdrawal of thyroid hormone therapy

Changes in the pituitary-thyroid axis in patients with Hashimoto's thyroiditis following withdrawal of thyroid suppressive therapy were analyzed. The group of patients with thyroid adenoma served as control (group I). Patients with Hashimoto's thyroiditis were divided into 2 groups on the basis of serum TSH levels 8 weeks after discontinuing the exogenous thyroid hormone (group II, less than 10 microunits/ml; group III, more than 10 microunits/ml). During treatment with L-T4(200 micrograms/day) or L-T3(50 micrograms/day), there was no significant difference in serum T4-I and T3 levels among the three groups. Following L-T4 withdrawal, basal serum TSH levels were higher at 2 to 8 weeks in groups II and III than in group I. Serum TSH response to TRH was greater at 4 to 8 weeks in groups II and III than in group I. Following L-T3 withdrawal, basal serum TSH levels were higher at 1 and 2 weeks in group II than in group I, while those of group III were consistently higher during the study. Higher TSH responses to TRH were observed at 1 to 8 weeks in groups II and III. Neither basal nor TRH-induced prolactin (PRL) secretion differed significantly among the three groups. We have demonstrated that pituitary TSH secretion in patients with Hashimoto's thyroiditis is affected more by withdrawal of thyroid hormone therapy than in patients with thyroid adenoma. In addition, the present findings suggest a difference between the sensitivity of thyrotrophs and lactotrophs in Hashimoto's thyroiditis after prolonged thyroid therapy is discontinued.     

Sepsis leads to thyroid impairment and dysfunction in rat model

Sepsis was a systemic response to a local infection. Apoptosis was observed in the experimental sepsis. In this study, cecal ligation and puncture (CLP)-induced sepsis was established in rats. We found that sepsis decreased thyroid hormone levels, including triiodothyronine (T3), thyroxine (T4), free T3 (fT3), and free T4 (fT4). Besides, we detected the increasing expression level of Caspase-3 and increasing ratio of TUNEL positive cells in the thyroid after sepsis. Furthermore, a series of pathological ultrastructural changes were observed in thyroid follicular epithelial cells by CLP-induced sepsis. This study established a sepsis animal model and provided the cellular and molecular basis for decoding the pathological mechanism in thyroid with the occurrence of sepsis.     

Weight Loss Through Gastric Banding: Effects on TSH and Thyroid Hormones in Obese Subjects With Normal Thyroid Function

Studies on thyroid function in obesity yielded inconsistent results; high thyroid‐stimulating hormone (TSH) levels were generally shown; high free triiodothyronine (fT)‐3 or fT4 levels were described in some, but not in other studies. After weight loss, TSH and thyroid hormones have been described to either increase or decrease. Our aim was to describe TSH, fT3, and fT4 in obese subjects with normal thyroid function before and after durable and significant weight loss, obtained through laparoscopic gastric banding (LAGB), in comparison with nonobese subjects. TSH, fT3, fT4, and fT3/fT4 ratio (an index of D1 and D2 deiodinase activity), were evaluated in 99 healthy controls and in 258 obese subjects, at baseline and 6 months, 1 year, and 2 years after LAGB, together with indexes of glucose (glucose, insulin, homeostasis model assessment of insulin resistance index) and lipid (triglycerides, total and high‐density lipoprotein–cholesterol) metabolism, and anthropometric measures (BMI and waist circumference). Under basal conditions, TSH, fT3, and fT4 were all in the normal range, but higher in obese than in nonobese subjects, and fT3/fT4 ratio was normal; with weight loss, fT3 and fT3/fT4 ratio decreased in obese subjects, while fT4 increased and TSH remained steady; all values were again within the normal range. Albumin and cholesterol levels remained steady, while triglycerides, insulin, and homeostasis model assessment of insulin resistance decreased, and high‐density lipoprotein–cholesterol increased. These changes, however, do not modify TSH, letting us to hypothesize that the changes are due to a decrease of D1 and D2 deiodinase activities.     

Thyroid and hypoxic stress in the newt Triturus carnifex

When specimens of the newt Triturus carnifex, under anaesthesia by submersion in a 0.2% chlorbutol solution for 25 min, are isolated in a respiratory chamber at 18 degrees C containing water with only 1.3 ppm of oxygen, they consume the oxygen completely in about 3 hr, but they can stay alive for many more hours and wake up with no apparent exterior consequences. Hypoxia induces rapid onset of hepatic steatosis and melanosis, as well as a controlled haemolytic process involving a pool of red blood cells of the same order of size as that held as a reserve in the spleen by animals in an aerial habitat. At the origin of the phenomena is an intense response by the hypophysis, histologically detectable 1 hr from the onset of treatment and confirmed 2 hr later by a highly significant increase in the plasma thyroidstimulating hormone (TSH) concentration compared with the controls (41.5 +/- 13.7 microU/L vs. 15.5 +/- 6.2; P < 0.005). The thyroid follicles react by reabsorbing their colloid, but instead of an increase in the plasma free T3 and T4 concentrations, fT3 falls significantly (1.5 +/- 0.3 pg/mL vs., the 2.4 +/- 0.7; P < 0.05), whereas fT4 remains stationary (4.0 +/- 0.5 pg/mL vs. 4.6 +/- 0.8; N.S.). After 6 hr, the plasmatic TSH concentration is still higher than in the controls (27.0 +/- 3.0 microU/L vs. 15.5 +/- 6.2; P < 0.05), whereas fT3 and fT4 remain stable (1.5 +/- 0.3 and 4.4 +/- 0.5 pg/mL, respectively). If T3 or T4 labelled with 125I is administered prior to hypoxia, after 6 hr of treatment the radioactivity is found to be limited exclusively to the liver and kidney; the thyroid, gall bladder and gut result negative, and this does not agree with hypotheses of hormone inactivation by deiodination, sulphation or glucuronidation. This apparently peculiar endocrine path has not been observed in previous studies on hypoxia in vertebrates, because the experiments were always designed to analyse plasma hormone levels after at least 24 hr of hypoxia or during chronic treatments, losing the most interesting phases of the endocrine response. The possibility that the hypoxic newt possesses alternative or complementary metabolic pathways to anaerobic glycolysis to sustain steatogenesis and melanogenesis and maintain the same cardiac activity as the controls is briefly discussed.     

The Relation Between Human Exposure to Mercury and Thyroid Hormone Status

The aim of this study was to investigate total mercury (THg) and methylmercury (MeHg) exposure of 75 mother-child pairs in relation to their thyroid hormone status (thyroid-stimulating hormone (TSH), triiodothyronine (T3), free triiodothyronine (fT3), thyroxine (T4), and free thyroxine (fT4)). THg and MeHg in blood samples were measured by atomic absorption spectrometry and gas chromatography-inductively coupled plasma-mass spectrometry, respectively. The median THg and MeHg levels in maternal blood, cord blood, and blood of 6-month-old children were 0.50, 0.53, and 0.32 and 0.22, 0.32, and 0.08 μg/L, respectively. There were significant correlations between paired maternal-cord blood levels for THg and MeHg, with a greater transplacental transport of MeHg compared with THg (mean cord/maternal blood ratio, 1.80 vs. 1.24). The maternal blood THg was found to be a better predictor of TSH levels in children than their current THg exposure. There was a positive correlation between maternal THg and children's TSH. T3 and fT3 levels in children were negatively related to cord blood THg in the majority (Caucasian) subgroup, whereas these associations were positive in the Roma subgroup. Mothers with dental amalgam fillings had significantly lower T4 and fT4 levels. Moreover, fT4 in the mothers of boys negatively correlated with maternal THg levels. MeHg exposure lowered T3 levels in the mothers of girls. Our results suggest that low-level exposure to Hg can affect thyroid hormone status during prenatal and early postnatal exposure depending on the form of Hg, gender, ethnicity, lifestyle, or socioeconomic status (dental amalgam fillings).     

Bioelement effects on thyroid gland in children living in iodine-adequate territory

Endemic goitre is a primary pathology of thyroid gland and critical medico social problem in many countries. A dominant cause of endemic goitre is iodine deficiency. However, besides primary iodine deficiency, the goitre may probably develop due to effects of other bioelement imbalances, essential to thyroid function maintenance. Here we studied 44 cases of endemic goitre in prepubertal children (7–10 y.o.) living in iodine-adequate territory. Thyroid volume was estimated by ultrasonometry. Main bioelements (Al, Ca, Cd, Co, Cr, Cu, Fe, Hg, I, Mg, Mn, Pb, Se, Si, Zn) were determined in hair samples by ICP-OES/ICP-MS method. Relationships between hair content of bioelements and thyroid gland size were estimated by multiple regressions. The regression model revealed significant positive relations between thyroid volume and Cr, Si, Mn contents. However, the actual factor of thyroid gland increase was only Si excess in organism. Significant negative relations of thyroid volume were revealed with I, Mg, Zn, Se, Co and Cd. In spite of this, the actual factors of thyroid gland volume increasing were I, Co, Mg and Se deficiency. Total bioelement contribution in thyroid impairment was estimated as 24%. Thus, it was suggested that endemic goitre in iodine-adequate territory can be formed by bioelement imbalances, namely Si excess and Co, Mg, Se shortage as well as endogenous I deficiency in spite of iodine-adequate environment.     

Aspiration cytology of Hashimoto's thyroiditis in an endemic area

Fine needle aspiration (FNA) plays a significant role in the diagnosis of thyroid lesions due to its simplicity and low cost. Hashimoto's thyroiditis (HT) is the second most common thyroid lesion next to endemic goitre diagnosed on FNA in iodine (I2) deficient areas. Data on its incidence, prevalence and clinicopathological features in I2 deficient areas is scanty compared to I2 sufficient areas. In the present study the patients presented with HT a decade earlier than reported in I2 sufficient areas. Presentation as a nodular thyroid is common. Diagnosis of HT is likely to be missed in smears showing cytological evidence of hyperplasia or abundant colloid. HT was concurrent in 20 cases of endemic goitre. Careful screening for Hurthle cell change and lymphocytic infiltration into follicular cells should be carried out. In equivocal cases multiple punctures and immunological investigations are helpful. In antibody-negative cases repeat FNA at follow-up is useful. Marked lymphocytic infiltration and Hurthle cell change may indicate a hypothyroid state but hormonal levels are required for clinical management.     

Maternal thyroid function in early and late pregnancy.

Thyroid function was investigated during and after pregnancy in 12 healthy euthyroid women. During pregnancy, serum total T4 (TT4) levels were significantly elevated and nearly stable, while thyroxine-binding globulin (TBG) levels progressively increased till the 7th month. A slight elevation, though not significant, of free T4 (fT4) was recorded in early pregnancy. In the following months, fT4, free T3 (fT3) and the T4/TBG ratio progressively diminished, reaching a plateau at the 7th month. Serum TSH levels, measured by an ultrasensitive immunofluorometric assay, were comparable to postpartum values during the first trimester and showed a moderate upward trend with the progression of pregnancy. The evaluation of 24-hour TSH profiles was performed in 5 women during the first trimester of pregnancy. In all women, the circadian rhythm of TSH was present with a normal nocturnal surge, though anticipated in 1 case. In summary (1) during the first trimester of pregnancy, the increased thyroid activity does not seem to be only sustained by pituitary TSH which remains unmodified; the negative correlation between TSH and hCG levels might suggest that hCG also stimulates the gland to increase thyroid hormone output, and the presence of a normal TSH circadian rhythm indicates that the central mechanism of neuroregulation of the pituitary-thyroid axis is preserved in early pregnancy, and (2) in late pregnancy, a marked decrease in free thyroid hormone fractions is accompanied by serum TSH levels still in the normal range, indicating a modification of thyroid homeostasis which might recognize various etiological factors.     

Low-T3 syndrome and signal-averaged ECG in haemodialysed patients

The study was designed to evaluate the potential link between low-T3 syndrome and signal-averaged ECG parameters (SAECG) in a group of hemodialyzed patients (HD-pts). 52 selected HD-pts (without relevant thyroid and cardiac diseases) were included. SAECGs were performed postdialysis together with evaluating free triiodothyronine (fT3), free thyroxine (fT4), reverse triiodothyronine (rT3), thyroid stimulating hormone levels and echocardiography. For each SAECG, QRS duration (QRSd), root-mean-square voltage of the terminal 40 ms of the QRS (RMS40), and low-amplitude signal duration (LAS40) were measured. Abnormal SAECGs were found in 30.8 % of HD-pt. HD-pts with decreased fT3 and increased rT3 values (low-T3 positive) revealed higher QRSd and LAS40 values in comparison with low-T3 negative HD-pts (p = 0.019, p < 0.001 respectively). Low-T3 positive HD-pts had lower RMS40 values than low-T3 negative patients (p < 0.001). The Pearson test showed significant correlations between QRSd and fT3 (r = -0.592, p < 0.001); QRSd and rT3 (r = 0.562, p < 0.001); RMS40 and fT3 (r = 0.432, p = 0.009); RMS40 and rT3 (r = -0.325, p = 0.025). On multivariate analysis, both fT3 and rT3 levels were found to be independent predictors of QRSd and RMS40 values. Our study showed that decreased fT3 and increased rT3 concentrations due to low-T3 syndrome influence SAECG parameters in HD-pt.