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Free Thyroxine (free + thyroxine)
Selected AbstractsThe Evaluation of Thyroid Functions, Thyroid Antibodies, and Thyroid Volumes in Children with Epilepsy during Short-Term Administration of Oxcarbazepine and ValproateEPILEPSIA, Issue 11 2006Ali Cansu Summary:,Purpose: The aim of this study was to evaluate the effects of short-term oxcarbazepine (OXC) and valproate (VPA) monotherapy on thyroid functions in children. Methods: Fifty-five newly diagnosed epileptic children with normal thyroid functions (confirmed with the thyrotropin releasing hormone stimulation test) participated in this study. VPA treatment was started in 30 patients and OXC in 25 patients. Serum thyroxine (T4), free thyroxine (fT4), triiodothyronine (T3), free triiodothyronine (fT3), reverse T3 (rT3), thyroid peroxidase antibodies (TPO-ab), and urine iodine levels were evaluated at baseline and at the third and sixth months of therapy. Results: In the OXC group, serum T4, fT4, T3, fT3, and rT3 levels were found to be decreased at the third and sixth months, the differences were significant compared to the baseline values except for fT3 levels at the third month and fT4 and rT3 levels at the sixth month (p < 0.05). At the sixth month, serum T4 level dropped below the normal reference value in 8 (32%), fT4 in 5 (20%), T3 in 4 (16%), and fT3 in 3 (12%) patients. In the VPA group, mean T4, fT4, T3, fT3, and rT3 levels at 3 and 6 months remained similar compared to the baseline values (p > 0.05). Mean serum thyroid stimulating hormone levels increased significantly at the sixth month compared to the baseline values in the VPA group (p < 0.05) while it remained unchanged in the OXC group (p > 0.05). There was no effect of either drug on urinary iodine excretion and serum TPO-ab levels remained in normal ranges throughout the study. Conclusions: In this prospective study, it is documented that children under short-term OXC or VPA therapy showed altered thyroid functions similar to the changes observed after long-term treatment. Although, the clinical significance of these results need to be evaluated with future studies, this observation of altered thyroid functions points out that thyroid functions may need to be monitored closely in children receiving antiepileptic treatment, even in the short-time interval. [source] Thyroid Function in Girls with Epilepsy with Carbamazepine, Oxcarbazepine, or Valproate Monotherapy and after Withdrawal of MedicationEPILEPSIA, Issue 3 2004Leena K. Vainionpää Summary: Purpose: Antiepileptic drugs may affect the serum thyroid hormone concentrations. The aim of this study was to evaluate thyroid function in 78 girls taking carbamazepine (CBZ), oxcarbazepine (OXC), or valproate (VPA) monotherapy for epilepsy and after withdrawal of the treatment. Methods: Forty-one girls taking VPA, 19 taking CBZ, and 18 taking OXC for epilepsy, as well as 54 healthy age-matched controls, aged 8 to 18 years, participated in the study. All the girls were examined clinically, and their pubertal stage was assessed. Blood samples were obtained for thyroid hormone and antibody assays. These examinations were repeated after a mean follow-up of 5.8 years to assess thyroid function, and 64 (82%) of 78 patients and 42 (78%) of 54 controls agreed to participate in the second evaluation. Results: In the first evaluation, the mean serum thyroid hormone concentrations were lower in the girls taking CBZ [thyroxine (T4), 70.2; SD, 10.9 nM; and free thyroxine (FT4), 11.5; SD, 1.8 pM] or OXC (T4, 74.9; SD, 16.4 nM; and FT4, 11.3; SD, 1.8 pM) than in the control girls (T4, 96.6; SD, 15.1 nM, and FT4, 14.4; SD, 1.5 pM; p < 0.001, all comparisons). However, thyrotropin (TSH) concentrations were normal in the girls taking CBZ or OXC. Sixty-three% of the girls taking CBZ and 67% of the girls taking OXC had serum T4 and/or FT4 levels below the lower limit of the reference range. The VPA-treated girls with epilepsy had normal serum T4 and FT4 concentrations, but slightly increased TSH levels (3.3; SD, 1.5 mU/L; p < 0.01) compared with the control girls (2.5; SD, 1.0 mU/L). Normal serum hormone concentrations were restored in the patients who discontinued the medication. Conclusions: Both CBZ and OXC reduce serum thyroid hormone concentrations in girls with epilepsy. Conversely, VPA is associated with normal serum thyroid hormone and increased thyrotropin levels. However, our results suggest that the changes in serum thyroid hormone and thyrotropin levels are reversible after withdrawal of the medication. [source] Thyroid hormone responses to endurance exerciseEQUINE VETERINARY JOURNAL, Issue S36 2006E. A. GRAVES Summary Reasons for performing study: Limited information exists about changes in circulating thyroid hormone concentrations during prolonged endurance exercise in horses. Objective: To examine the effects of prolonged exercise on serum iodothyronine concentrations in horses performing endurance exercise of varying distances. Methods: Serum concentrations of iodothyronines were measured in horses before and after completion of 40, 56, 80 and 160 km endurance rides (Study 1); daily during a 5 day, 424 km endurance ride (Study 2); and before and for 72 h after completion of a treadmill exercise test simulating a 60 km endurance ride (Study 3). Results: In Study 1, 40 and 56 km of endurance exercise had little effect on serum iodothyronine concentrations with the exception of a 10% decrease (P<0.05) in free thyroxine (FT4) concentration after the 56 km ride. In contrast, total thyroxine (T4), total triiodothyronine (T3), FT4 and free triiodothyronine (FT3) concentrations all decreased (P<0.05) after successful completion of 80 and 160 km rides, with decreases ranging from 13,31% and 47,54% for distances of 80 and 160 km, respectively. Further, pre-ride T4 concentration was lower (P<0.05) and FT3 concentration was higher (P<0.05) in horses competing 160 km as compared to horses competing over shorter distances. In Study 2, serum concentrations of T4, T3 and reverse triiodothyronine (rT3) progressively decreased (P<0.05) over the course of the multi-day ride. In Study 3, the greatest decrease (P<0.05) in all iodothyronines was observed at 12 h of recovery, ranging from 25% for FT4 to 53% for FT3, but all thyroid hormone concentrations had returned to the pre-exercise values by 24 h of recovery. Conclusion: Endurance exercise results in transient decreases in serum iodothyronine concentrations. Potential relevance: These data are important to consider when thyroid gland function is assessed by measurement of serum iodothyronine concentrations in endurance horses. [source] Interference in thyroid-stimulating hormone determinationEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 8 2010Mauro Imperiali Eur J Clin Invest 2010; 40 (8): 756,758 Abstract Background, Thyroid-stimulating hormone (TSH) measurement plays a major role in the diagnosis of thyroid disorders. Despite the good quality of immunochemical tests measuring TSH levels, the presence of interfering substances can sometimes alter the TSH results. Design, We reported the case of a 79-year-old man affected by primary autoimmune hypothyroidism hospitalized for pneumonia. A TSH value > 100 mIU L -1 (reference: 0.44 mIU L -1) was found at admission. No signs and symptoms of hypothyroidism were found upon clinical examination and serum concentration of the free thyroxine (FT4) was normal. Results, Serum treatment in heterophile antibody blocking tubes did not change the TSH result in our assay, while normal levels were found in a different immunoassay method. An abnormal pattern was found in protein electrophoresis at admission, with IgG / j and IgM / k monoclonal bands proved in immunofixation. Interestingly, the disappearance of monoclonal bands was paralleled with a normalization of the TSH value. Conclusions, We suggest in this study that the TSH determination might be influenced by the presence of transient paraproteins. [source] Relationships of serum free thyroxine and erythrocyte measures in euthyroid HFE C282Y homozygotes and control subjects: the HEIRS StudyINTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 3 2010J. C. BARTON Summary Hemoglobin (Hb) levels and mean corpuscular volume (MCV) are abnormal in some persons with hemochromatosis or thyroid disorders. We sought to determine whether serum free thyroxine (T4) affects erythrocyte measures in euthyroid adults with or without C282Y homozygosity. We evaluated 488 white HFE C282Y homozygotes and controls (no HFE C282Y or H63D; normal serum iron measures) identified in screening; we excluded those with thyroid disorders, anemia, erythrocytosis, or serum ferritin (SF) <34 pmol/l. In the remaining 141 C282Y homozygotes and 243 controls, we evaluated correlations of log10 free T4 with Hb, RBC, MCV, and red blood cell distribution width (RDW). C282Y homozygotes had lower mean age, higher mean Hb, MCV, and log10 SF, and lower mean RBC and RDW than controls; mean log10 free T4 did not differ significantly. In HFE C282Y homozygotes, there was no significant correlation of log10 T4 with erythrocyte measures. In controls, there was a positive correlation of log10 T4 with Hb (P = 0.0096) and a negative correlation with RDW (P = 0.0286). Among euthyroid white adults without iron deficiency, there are significant correlations of log10 free T4 with Hb and RDW in controls, but not in HFE C282Y homozygotes. [source] Does diagnostic sonography alter thyroid and parathyroid hormone levels?JOURNAL OF CLINICAL ULTRASOUND, Issue 1 2008Erdinc Serin MD Abstract Purpose To investigate possible alterations in the levels of thyroid and parathyroid hormones (PTHs) and thyroglobulin (TG) in healthy individuals following diagnostic sonographic examination of the thyroid gland. Methods Thirty healthy women with no pathologic findings underwent sonographic examination, followed 6 weeks later by a second examination involving a probe-only application (PA) with the ultrasound scanner switched off. Duration times were identical for both examinations. Blood was drawn before and after the 2 applications. Thyroid hormone, PTH, and TG levels before and after the 2 applications were compared, and the difference between the variations for each parameter in the first and second applications was assessed. Blood samples were taken before and after the sonographic examination and the PA, and the serum concentrations of sensitive thyrotropin, total and free thyroxine, total and free tri-iodothyronine, TG, and PTH were measured. The pre- and post-examination levels of the hormones for the 2 applications were then compared and the difference between the variations for each parameter in the first and second application was then assessed. Results The only significant variations observed were in the TG levels after PA and PTH levels after both sonographic examination and PA. The comparison between the 2 difference values revealed no significant difference except for PTH. Conclusion This preliminary report on the possible influence of sonographic examination of the thyroid on the serum levels of thyroid and parathyroid hormones suggests that gland secretions such as PTH may be affected by external factors, including ultrasound. Clinicians should be aware of alterations in hormone levels by external factors. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2008 [source] Altered Thyroid Hormones and Behavioural Change in a Sub-Population of Rats Following Chronic Constriction InjuryJOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2010E. Kilburn-Watt Hypothyroidism is associated with a disturbance of behaviour and mood. There are also individuals, not classified as hypothyroid, with low to ,low normal' thyroid hormone levels and normal thyroid-stimulating hormone (TSH) levels who have mood and behavioural changes. As the peripheral thyroid hormones decrease, TSH is expected to increase. However, there are a number of physiological mechanisms known to suppress TSH. In the present study, we report on thyroid hormone regulation in a rat model of neuropathic pain and altered social behaviour that is usually transient, but is persistent in a sub-group of the population. Following ligation of the sciatic nerve, male Sprague-Dawley rats were assessed for social dominance towards an intruder: 20% showed persistently decreased social dominance. Plasma levels of thyroid hormones, TSH and corticosterone were measured before and on days 2, 3, 4, 5 and 6 after injury in 21 rats. The mean plasma thyroxine (T4), free thyroxine (fT4) and triiodothyronine (T3) levels decreased significantly post-injury in rats with persistently changed behaviour compared to rats with unchanged behaviour (P , 0.002). There was no significant difference between groups for mean change in free triiodothyronine (fT3) or TSH. There was a correlation between decreased dominance behaviour and decrease in both T4 (r = 0.62, P = 0.009) and fT4 (r = 0.71, P = 0.001), but no correlation with TSH. In a sub-population of rats, decreased thyroid hormones did not result in the expected increased levels of TSH to restore pre-injury levels, nor did they show increased hypothalamic thyrotrophin-releasing hormone mRNA expression, indicating altered hypothalamic-pituitary-thyroid axis regulation. Because T3 availability to the brain is dependent on both circulating T3 and T4, decreased peripheral thyroid hormones may result in changed neural function, as expressed in altered complex behaviours in this sub-population of rats. [source] Measurement of Free Thyroxine Concentration in Horses by Equilibrium DialysisJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 2 2006Babetta A. Breuhaus The purpose of the study reported here was to validate measurement of free thyroxine (fT4) concentration in equine serum by equilibrium dialysis (fT4D), and to compare values with fT4 concentration measured directly and with total T4 (TT4) concentration. The fT4D, fT74, and TT4 concentrations were measured over a range of values in euthyroid horses and horses made hypothyroid by administration of propylthiouracil (PTU). Concentrations of fT4D (<1.8,83 pmol/L) were consistently higher than those of fT4 (<1,40 pmol/L). There was a significant (P < .001) regression of fT4D on fT4 in 503 samples from normal horses (y = 2.086x - 0.430). In baseline samples from 71 healthy euthyroid horses, fT4 concentration ranged from 6- 21 pmol/L (median, 11 pmol/L; 95% confidence interval [CI]10.5,11.8 pmol/L), and fT4D concentration ranged from 7,47 pmol/L (median, 22 pmol/L; 95% CI 20.9,25.1 pmol/L). Free T4D, fT4, and TT4 concentrations were also measured in 34 ill horses. Horses consuming PTU and ill horses had significantly (P < .05) lower serum concentration of TT4, fT4, and fT4D than did clinically normal, healthy horses. If serum samples from ill horses were further subdivided into samples from horses that lived and samples from horses that died, fT4D concentration was not significantly different in ill horses that lived, compared with that in healthy horses, whereas fT4 concentration was still significantly decreased in ill horses that died (P < 0.001). We conclude that measurement of fT4 concentration by equilibrium dialysis is a valid technique in the horse, and its use may provide improved ability to distinguish nonthyroidal illness syndrome from hypothyroidism in that species. [source] Investigation of the relationship between low Apgar scores and early neonatal thyroid functionPEDIATRICS INTERNATIONAL, Issue 5 2000Erbil Sak Abstract Background: The aim of the present study was to assess the effects of low Apgar scores on perinatal thyroid function. Methods: Forty full-term infants delivered by the normal spontaneous vaginal route were enrolled into the study. All babies had 1 and 5 min Apgar scores below 4. The control group consisted of 26 full-term healthy neonates. Cord blood and serum tri-iodothyronine (T3), thyroxine (T4), reverse tri-iodothyronine (rT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH) and thyroid-binding globulin (TBG) determinations were performed by an enzyme immunoassay method. Results: The mean values of FT4 and T4 observed in the cord blood of the study group were significantly lower compared with matched controls, whereas the mean TSH values were significantly higher. There were no differences in concentrations of T3, rT3 and TBG between the two groups. Conclusions: These results demonstrate the existence of transient hypothyroidism at birth in babies with Apgar scores below 4 delivered by the spontaneous vaginal route. [source] Relationship between serum leptin and thyroid hormones in childrenPEDIATRICS INTERNATIONAL, Issue 3 2000MAKOTO UCHIYAMA, Tadashi Asami TATIANA CIOMARTEN Abstract Background: Because leptin decreases food intake and increases energy expenditure, the possible influence of thyroid status on the leptin system has been investigated mainly in adults and animals. However, the data available at present are very confusing. The aim of the present study was to assess the possible interaction of thyroid hormones with the leptin system. Methods: Serum free thyroxine (FT4), a biologically active thyroid hormone, and thyroid stimulating hormone (TSH), a sensitive and reliable index of thyroid status, were examined in 51 children (19 males, 32 females) with mass screening-detected congenital hypothyroidism on continuous L -thyroxine (L-T4) substitution therapy. The subjects were divided into younger (n=35, aged 1 month , 5 years) and older (n=16, 6 years , 11 years) children groups. Serum levels of leptin and thyroid hormones were measured in the subjects. Body mass index (BMI) was estimated by the formula bodyweight (kg)/height`height (m 2), which is known as the Kaup index in younger children and BMI in older children and adults. Results: In the younger children group, serum leptin levels showed no correlation with serum TSH, FT4 or T4. In the older children group, serum leptin concentrations significantly correlated with T4 (r=0.510, P<0.05) and BMI (n=16, r=0.647, P<0.01), but not with TSH or FT4. Conclusion: The role of thyroid hormones in modulating leptin synthesis and secretion seems to have little, if any, clinical or biological relevance. [source] Hypothyroidism in neonates post-iodinated contrast media: a systematic reviewACTA PAEDIATRICA, Issue 10 2009Alexandra Ahmet Abstract Aim:, To determine if neonates exposed to iodinated contrast media are at risk of hypothyroidism. Methods:, A systematic review was conducted by searching electronic databases (e.g. MEDLINE), contacting experts and scanning reference lists. Studies examining the effects of contrast media on neonatal thyroid function were included. Two reviewers independently screened the literature and assessed the risk of bias, while one reviewer abstracted data. Results:, Eleven studies were included; nine studies directly examined the risk of hypothyroidism (n = 182 neonates exposed to contrast media). All were highly affected by bias. In the three studies including term infants, one showed a trend towards increased thyroid-stimulating hormone (TSH) and decreased free thyroxine (FT4) among exposed groups. Six of 72 (8.3%) term infants exposed were treated for hypothyroidism. In studies of premature infants, there was a trend towards increased TSH (n = 3/7 studies), lower total thyroxine (n = 1), decreased triidothyronine and FT4 (n = 3) and hypothyroidism (n = 5). Twenty of 110 (18.2%) premature infants exposed were treated for hypothyroidism. Conclusion:, Hospitalized neonates exposed to iodinated contrast media are at risk for abnormal thyroid function and development of hypothyroidism. Premature infants might be at increased risk. Well-controlled studies are required to replicate our findings because the included studies were highly affected by bias. [source] | ||||||||||