triiodothyronine--reverse and Thyroid-Diseases

Thyroxine and triiodothyronine (T3) are classical thyroid hormones and with relatively well-understood actions. In contrast, the physiological role of thyroid hormone metabolites, also circulating in the blood, is less well characterized. These molecules, namely, reverse triiodothyronine, 3,5-diiodothyronine, 3-iodothyronamine, tetraiodoacetic acid and triiodoacetic acid, mediate both agonistic (thyromimetic) and antagonistic actions additional to the effects of the classical thyroid hormones. Here, we provide an overview of the main factors influencing thyroid hormone action, and then go on to describe the main effects of the metabolites and their potential use in medicine. One section addresses thyroid hormone levels in corona virus disease 19 (COVID-19). It appears that i) the more potently-acting molecules T3 and triiodoacetic acid have shorter half-lives than the less potent antagonists 3-iodothyronamine and tetraiodoacetic acid; ii) reverse T3 and 3,5-diiodothyronine may serve as indicators for metabolic dysregulation and disease, and iii) Nanotetrac may be a promising candidate for treating cancer, and resmetirom and VK2809 for steatohepatitis. Further, the use of L-T3 in the treatment of severely ill COVID-19 patients is critically discussed.

Topics: Comorbidity; COVID-19; Diiodothyronines; Humans; Iodide Peroxidase; SARS-CoV-2; Thyroid Diseases; Thyroid Hormones; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

The hypothalamic-pituitary-thyroid axis plays a key role in skeletal development, acquisition of peak bone mass and regulation of adult bone turnover. Euthyroid status is essential for maintenance of optimal bone mineralization and strength. In population studies, hypothyroidism and hyperthyroidism have both been associated with an increased risk of fracture. Furthermore, recent studies in healthy euthyroid post-menopausal women indicate that thyroid status in the upper normal range is also associated with low bone mineral density and an increased risk of non-vertebral fracture. Studies in mutant mice have demonstrated that thyroid hormone receptor α is the major mediator of T3 action in bone and that thyroid hormones exert anabolic actions during growth but have catabolic effects on the adult skeleton. Nevertheless, TSH has also been proposed to be a direct negative regulator of bone turnover, although the relative importance of T3 and TSH actions in the skeleton has yet to be clarified.

Topics: Animals; Bone and Bones; Bone Remodeling; Humans; Thyroid Diseases; Thyroid Gland; Thyrotropin; Triiodothyronine, Reverse

Changes in thyroid function and structure during pregnancy, including abnormalities in thyroid ultrasonography. Levels of thyroid stimulating hormone (TSH), free thyroxine (FT4), total thyroxine (TT4), total triiodothyronine (TT3), reverse triiodothyronine (rT3), thyroxin binding globulin (TBG) and thyroglobulin (Tg) as well as the changes in metabolism have been presented. Difficulties in the diagnostics of hyperthyroidism and hypothyroidism in pregnant women have been described. In addition modern ideas about the treatment of thyroid dysfunction in this period of woman life have been presented. Furthermore thyroid physiology and pathology in fetus and newborn have been described.

Topics: Female; Humans; Hyperthyroidism; Hypothyroidism; Infant, Newborn; Pregnancy; Pregnancy Complications; Thyroglobulin; Thyroid Diseases; Thyroid Function Tests; Thyroid Gland; Thyroid Hormones; Thyrotropin; Thyroxine; Thyroxine-Binding Proteins; Triiodothyronine; Triiodothyronine, Reverse

While a wide variety of thyroid function tests are currently available, all are sometimes abnormal in patients without thyroid disease. To interpret test results properly, the clinician needs to be aware of factors altering thyroid function tests. In every instance, the clinician needs to begin by asking whether the patient is thyrotoxic or hypothyroid and then should order a test to substantiate or exclude the diagnosis. In this way, accurate and early diagnosis of thyroid dysfunction can be routinely established.

Topics: Algorithms; Diagnosis, Differential; Humans; Thyroid Diseases; Thyroid Function Tests; Thyroid Gland; Thyrotropin; Thyrotropin-Releasing Hormone; Thyroxine; Thyroxine-Binding Proteins; Triiodothyronine; Triiodothyronine, Reverse

"Syndromes related to defective iodothyronine metabolism" have been frequently observed in clinical practice. As for methodological and pathophysiological reasons T4, T3, rT3 and TSH estimations are of limited value in these situations, thus, the interpretation of the laboratory findings becomes frequently difficult. Furthermore determining the individual "whole body"- or "organ-thyroid state" requires more than measuring the serum concentrations of thyroid hormones. Iodothyronine metabolism is strongly organ specific, therefore, alterations in plasma thyroid hormone concentrations cannot reflect the specific cellular and subcellular thyroid hormone concentrations of individual organs. However, there is some experimental evidence, that disease-induced alterations in plasma thyroid hormone levels are a simple reflection of the catabolic state of the organisms. At present the biological implication of altered thyroid hormone economy in non-thyroidal illness should not be considered as an energy sparing, i.e. protein sparing effect, anymore: Thyroid hormones in their physiological concentrations act as anabolic hormones. There is no general indication for substituting diminished T3. Up to now, preliminary data suggest the benefit of T3-substitution in septic shock or in "respiratory distress syndrome". However, the possible benefit of improved cardiovascular of respiratory function should be compared carefully to the harm of the therapy, i.e. T3-induced increase in protein catabolism or possible deterioration in preexisting ischemic heart disease: From a clinical point of view, most of non-thyroidal illness-induced changes in ITH-metabolism seem to implicate a pitfall in physician's diagnosis of the thyroid state rather than a therapeutic question.

Topics: Body Temperature Regulation; Catecholamines; Glucose; Humans; Infant, Newborn; Iodide Peroxidase; Ketone Bodies; Models, Biological; Respiratory Distress Syndrome, Newborn; Shock, Septic; Syndrome; Thyroglobulin; Thyroid Diseases; Thyroid Gland; Thyronines; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adrenal Gland Diseases; C-Peptide; Diabetes Mellitus; Dwarfism; Glucagon; Growth Hormone; Humans; Insulin; Parathyroid Diseases; Radioimmunoassay; Thyroglobulin; Thyroid Diseases; Thyroxine; Thyroxine-Binding Proteins; Triiodothyronine; Triiodothyronine, Reverse

Modern day evaluation of thyroid disorders requires a combination of accurate clinical judgement and reliable, sensitive, and specific thyroid functions tests. Principle among the latter are thyroxine (T4) 3, 5, 3'-triiodothyronine (T3), and thyroid-stimulating hormone (TSH). Also playing an important role in special situations are free thyroxine, an assessment of bound and unbound thyroid-binding globulin, TRH stimulation, long-acting thyroid stimulator (LATS), antibodies to thyroid hormone and to thyroid receptors. Basic to interpretation of these tests in the clinical setting is a comprehension of the relationship of the hypothalamus, the pituitary, and the thyroid gland as well as a knowledge of the peripheral metabolism of thyroxine and triiodothyronine. The role of each of these laboratory tests in the evaluation of hyper- and hypometabolic states, their alteration in nonthyroid and other endocrine disorders, and the effects of environmental and physiological factors on these tests are reviewed.

Topics: Adult; Aged; Autoantibodies; Calcitonin; Choriocarcinoma; Female; Fetus; Hepatitis; Humans; Hyperthyroidism; Hypothalamo-Hypophyseal System; Hypothyroidism; Infant, Newborn; Kidney Diseases; Male; Mental Disorders; Middle Aged; Pregnancy; Stress, Physiological; Thyroglobulin; Thyroid Diseases; Thyroid Function Tests; Thyroid Gland; Thyrotropin; Thyrotropin-Releasing Hormone; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adult; Aging; Animals; Chemical Phenomena; Chemistry; Chloramines; Cross Reactions; Diiodothyronines; Humans; Rabbits; Radioimmunoassay; Thyroid Diseases; Thyroid Function Tests; Thyroid Gland; Thyronines; Thyrotropin; Thyroxine; Tosyl Compounds; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adolescent; Adult; Aging; Alpha-Globulins; Animals; Body Fluids; Chemical Phenomena; Chemistry; Child; Child, Preschool; Cyclic AMP; Dexamethasone; Diet; Erythropoiesis; Female; Humans; Infant; Infant, Newborn; Ipodate; Kinetics; Male; Prealbumin; Radioimmunoassay; Serum Albumin; Thyroid Diseases; Thyrotropin; Thyrotropin-Releasing Hormone; Thyroxine; Thyroxine-Binding Proteins; Triiodothyronine; Triiodothyronine, Reverse

Topics: Animals; Feedback; Homeostasis; Humans; Hypothalamo-Hypophyseal System; Hypothyroidism; Infant, Newborn; Infant, Newborn, Diseases; Infant, Premature; Rats; Receptors, Cell Surface; Receptors, Thyroid Hormone; Sheep; Thyroid Diseases; Thyroid Gland; Thyrotropin; Thyroxine; Thyroxine-Binding Proteins; Triiodothyronine; Triiodothyronine, Reverse

Topics: Anesthesia; Anesthetics; Animals; Humans; Iodine Radioisotopes; Rats; Stress, Physiological; Surgical Procedures, Operative; Thyroid Diseases; Thyroid Gland; Thyroid Hormones; Thyrotropin; Thyroxine; Thyroxine-Binding Proteins; Triiodothyronine; Triiodothyronine, Reverse

Topics: Humans; Thyroid Diseases; Triiodothyronine, Reverse

Thyroid hormone (TH) abnormalities are common in patients with diabetes mellitus (DM). These thyroid hormone abnormalities have been associated with inflammatory activity in several conditions but this link remains unclear in DM. We assessed the influence of subclinical inflammation in TH metabolism in euthyroid diabetic patients. Cross-sectional study involving 258 subjects divided in 4 groups: 70 patients with T2DM and 55 patients with T1DM and two control groups of 70 and 63 non-diabetic individuals, respectively. Groups were paired by age, sex, and body mass index (BMI). We evaluated the association between clinical and hormonal variables [thyrotropin, reverse T3 (rT3), total and free thyroxine (T4), and triiodothyronine (T3)] with the inflammation markers C-reactive protein (hs-CRP), serum amyloid A (SAA), and interleukin-6 (IL-6). Serum T3 and free T3 were lower in patients with diabetes (all P < 0.001) compared to the control groups. Interleukin-6 showed positive correlations with rT3 in both groups (P < 0.05). IL-6 was independently associated to FT3/rT3 (B = -0.193; 95% CI -0.31; -0.076; P = 0.002) and FT4/rT3 (B = -0.107; 95% CI -0.207; -0.006; P = 0.039) in the T1DM group. In the T2DM group, SAA (B = 0.18; 95% CI 0.089; 0.271; P < 0.001) and hs-CRP (B = -0.069; 95% CI -0.132; -0.007; P = 0.03) predicted FT3 levels. SAA (B = -0.16; 95% CI -0.26; -0.061; P = 0.002) and IL6 (B = 0.123; 95% CI 0.005; 0.241; P = 0.041) were related to FT4/FT3. In DM, differences in TH levels compared to non-diabetic individuals were related to increased subclinical inflammatory activity and BMI. Altered deiodinase activity was probably involved. These findings were independent of sex, age, BMI, and HbA1c levels.

Topics: Adult; Asymptomatic Diseases; C-Reactive Protein; Case-Control Studies; Cross-Sectional Studies; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Female; Humans; Inflammation; Interleukin-6; Male; Middle Aged; Serum Amyloid A Protein; Thyroid Diseases; Thyroid Function Tests; Thyroid Hormones; Triiodothyronine, Reverse; Young Adult

Perturbations in thyroid function are common in older individuals but their significance in the very old is not fully understood.. This study sought to determine whether thyroid hormone status and variation of thyroid hormones within the reference range correlated with mortality and disability in a cohort of 85-year-olds.. A cohort of 85-year-old individuals were assessed in their own homes (community or institutional care) for health status and thyroid function, and followed for mortality and disability for up to 9 years.. Six hundred and forty-three 85-year-olds registered with participating general practices in Newcastle and North Tyneside, United Kingdom.. All-cause mortality, cardiovascular mortality, and disability according to thyroid disease status and baseline thyroid hormone parameters (serum TSH, FT. After adjustment for age and sex, all-cause mortality was associated with baseline serum rT. Our study is reassuring that individuals age 85 y with both subclinical hypothyroidism and subclinical hyperthyroidism do not have a significantly worse survival over 9 years than their euthyroid peers. However, thyroid function tests did predict disability, with higher serum TSH levels predicting better outcomes. These data strengthen the argument for routine use of age-specific thyroid function reference ranges.

Topics: Aged, 80 and over; Cardiovascular Diseases; Dextrothyroxine; Disabled Persons; England; Female; Humans; Longitudinal Studies; Male; Mortality; Reference Values; Thyroid Diseases; Thyroid Function Tests; Thyrotropin; Triiodothyronine; Triiodothyronine, Reverse

Topics: Euthyroid Sick Syndromes; Humans; Infant, Newborn; Thyroid Diseases; Triiodothyronine; Triiodothyronine, Reverse

Thyroid function has been related to Alzheimer disease (AD), but it remains unclear whether thyroid dysfunction results from or contributes to developing AD.. The objective of the study was to determine the association between thyroid function and both medial temporal lobe atrophy on brain magnetic resonance imaging (MRI) as putative early sign of AD and risk of dementia.. This was a population-based cohort study among 1077 elderly subjects aged 60-90 yr and dementia free at baseline (1995-1996).. Nonfasting serum levels of TSH, free T(4) (fT(4)), T(3), and rT(3) were available in 1025 subjects followed up for incident dementia until 2005. In a subset of 489 nondemented elderly, we assessed volumes of the hippocampus and amygdala on brain MRI. Subjects using thyroid medication were excluded.. During 5657 person-years of follow-up (mean 5.5 yr), 63 subjects were diagnosed with dementia (46 with AD). TSH and thyroid hormones were not associated with risk of dementia or AD. TSH and T(3) were also not related to brain atrophy, whereas nondemented subjects with higher fT(4) levels had more hippocampal and amygdalar atrophy on MRI. Similar associations were found for rT(3). Excluding subjects with thyroid disorders or incipient AD did not change the results.. In our study, TSH was related neither to risk of AD nor with early MRI markers thereof, arguing against an important role of thyroid function in the development of AD. Whether the association of higher fT(4) and rT(3) levels with brain atrophy on MRI has functional significance remains to be elucidated.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amygdala; Atrophy; Cohort Studies; Dementia; Follow-Up Studies; Hippocampus; Humans; Magnetic Resonance Imaging; Middle Aged; Risk Factors; Temporal Lobe; Thyroid Diseases; Thyroid Gland; Thyroid Hormones; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Down Syndrome (DS) or trisomy 21 (T21) is the most frequent and the best known malformation syndrome associated with mental deficiency that appears in human,. Average incidence of this syndrome is about 1:700 newborns. Numerous researchers noted thyroid disorders in people with Down Syndrome but, clinical symptoms of thyroid dysfunction are difficult to separate from DS phenotype. The aim of this study was to examine the thyroid function in the patients with DS. Our results confirmed higher frequency of thyroid dysfunction in DS patients. Higher values of TSH were found in 60,34% of the examined DS patients, which is significantly higher value comparing with the control group (p<0,01). Compensated hypothyroidism was established in 27,92% of the examined DS patients, and most of those (63,23%) were younger than 6 years. The conclusions emphasize the necessity of implementation of thyroid function screening program in persons with DS, and the need for adequate treatment of its dysfunction. Thus, the symptoms of the disease would be alleviated and better physical and mental fitness ensured.

Topics: Adolescent; Age Factors; Child; Child, Preschool; Down Syndrome; Female; Humans; Infant; Infant, Newborn; Male; Thyroid Diseases; Thyroid Function Tests; Thyroid Gland; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

To evaluate the value of the thyrotropin-releasing hormone (TRH) stimulation test in the diagnostic work-up of the thyroid function in patients with pituitary pathology.. To compare the thyrotropin (TSH) response and the absolute and fold changes after TRH administration in 35 patients with pituitary pathology and 26 normal subjects.. Nine of the patients and 2 of the normal subjects had a pathological response. No difference in the thyrotropic response to TRH was found either for the actual values, or for the absolute or fold changes of TSH between the groups.. The role of the TRH test in the evaluation of thyroid function in patients with pituitary pathology is modest. The best variables for evaluation of the presence of central hypothyroidism are still a free thyroxine estimate combined with an inappropriately low TSH.

Topics: Adolescent; Adult; Aged; Female; Humans; Male; Middle Aged; Pituitary Diseases; Pituitary Gland; Reproducibility of Results; Thyroid Diseases; Thyrotropin-Releasing Hormone; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

To determine the effects of endotoxin administration on thyroid function test results and serum tumor necrosis factor-alpha (TNF-alpha) activity in healthy dogs.. 6 healthy adult male dogs.. Serum concentrations of thyroxine (T4), 3,5,3'-triiodothyronine (T3), 3,3'5'-triiodothyronine (rT3), free T4 (fT4), and endogenous canine thyroid stimulating hormone (TSH), and TNF-alpha activity were measured before (day-1; baseline), during (days 0 to 3), and after (days 4 to 24) IV administration of endotoxin every 12 hours for 84 hours.. Compared with baseline values, serum T3 concentration decreased significantly, whereas rT3 concentration increased significantly 8 hours after initial endotoxin administration. Serum T4 concentration decreased significantly at 8 and 12 hours after initiating endotoxin administration. Serum T4 concentration returned to reference range limits, then decreased significantly on days 6 to 12 and 16 to 20. Serum fT4 concentration increased significantly at 12, 24, and 48 hours after cessation of endotoxin treatment, compared with baseline values. Serum rT3 concentration returned to reference range, then decreased significantly days 5 and 7 after stopping endotoxin treatment. Serum TNF-alpha activity was significantly increased only 4 hours after initial endotoxin treatment, compared with baseline activity.. Endotoxin administration modeled alterations in thyroid function test results found in dogs with spontaneous nonthyroidal illness syndrome. A decrease in serum T4 andT3 concentrations and increase in serum rT3 concentration indicate impaired secretion and metabolism of thyroid hormones. The persistent decrease in serum T4 concentration indicates that caution should be used in interpreting serum T4 concentrations after resolution of an illness in dogs.

Topics: Animals; Dog Diseases; Dogs; Endotoxins; Male; Thyroid Diseases; Thyroid Function Tests; Thyroid Gland; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse; Tumor Necrosis Factor-alpha

To compare serum concentrations of thyroid hormones--T4, T3, free T4 (FT4) and reverse T3 (rT3)--and thyroid-stimulating hormone (TSH) found in the umbilical cord blood of term newborns with and without asphyxia and those found in their arterial blood collected between 18 and 24 h after birth. A further aim of the study was to assess the association between severity of hypoxic-ischemic encephalopathy and altered thyroid hormone and TSH levels, and between mortality and FT4 levels in the arterial blood of newborns between 18 and 24 h of life.. A case-control study was carried out. The case group comprised 17 term newborns (Apgar score < or = 3 and < or = 5 at the first and fifth minutes; umbilical cord blood pH < or = 7.15) who required bag and mask ventilation for at least one minute immediately after birth. The control group consisted of 17 normal, term newborns (Apgar score > or = 8 and > or = 9 at the first and fifth minutes; umbilical cord blood pH > or = 7.2). Cord blood and arterial blood samples were collected immediately after birth and 18 to 24 h after birth, respectively, and were used in the blood gas analysis and to determine serum concentrations of T4, T3, FT4, rT3 and TSH by radioimmunoassay. All newborns were followed-up until hospital discharge or death.. Gestational age, birthweight, sex, size for gestational age, mode of delivery and skin color (white and non-white) were similar for both groups. No differences were found in mean levels of cord blood TSH, T4, T3 and FT4 between the groups. In the samples collected 18 to 24 h after birth, mean levels of TSH, T4, T3 and FT4 were significantly lower in the asphyxiated group than in the control group. Mean concentrations of arterial TSH, T4 and T3 between 18 and 24 h of life were lower than concentrations found in the cord blood analysis in asphyxiated newborns, but not in controls. In addition, asphyxiated newborns with moderate/severe hypoxic-ischemic encephalopathy presented significantly lower mean levels of TSH, T4, T3 and FT4 than those of controls. None of the asphyxiated newborns with FT4 > or = 2.0 ng/dl died; 6 out of the 11 asphyxiated newborns with FT4 < 2.0 ng/dl died.. Serum concentrations of TSH, T4, T3 and FT4 are lower in asphyxiated newborns than in normal newborns between 18 and 24 h of life; this suggests central hypothyroidism secondary to asphyxia. Asphyxiated newborns with moderate/severe hypoxic-ischemic encephalopathy present a greater involvement of the thyroid function and consequently a greater risk of death.

Topics: Asphyxia Neonatorum; Case-Control Studies; Female; Fetal Blood; Humans; Hypoxia-Ischemia, Brain; Infant Mortality; Infant, Newborn; Male; Predictive Value of Tests; Risk Factors; Severity of Illness Index; Thyroid Diseases; Thyrotropin; Thyroxine; Time Factors; Triiodothyronine; Triiodothyronine, Reverse

To study transforming growth factor-beta1 (TGF-beta1) plasma concentrations in elderly patients with nonthyroidal illnesses (NTI).. Case-control study.. We measured plasma concentrations of tri-iodothyronine (T3), reverse T3 (rT3), thyroxine (T4), free T3 (fT3) and free T4 (fT4) estimates, TSH, and TGF-beta1 in 48 elderly NTI patients consecutively admitted in our Division of Internal Medicine and Metabolic Diseases, and in 11 healthy age- and sex-matched controls.. The data on thyroid hormones enabled us to identify three groups: Group A, subjects (8 patients) with T3 and fT3 levels comparable to those in controls: Group B, subjects (30 patients) with T3 and fT3 levels lower than controls but rT3 levels comparable to those of controls; Group C, subjects (10 patients) with T3 and fT3 levels lower than those of controls and higher rT3 levels. The patients of Group C showed higher plasma levels of TGF-beta1 compared with controls. Moreover, we found a positive correlation between TGF-beta1 and rT3 (rs = 0.38, P < 0.01) in the whole group of NTI patients.. Our data seem to confirm the hypothesis that TGF-beta1 could play a role in the pathogenesis of some modifications of thyroid function observed in patients with nonthyroidal illnesses.

Topics: Aged; Case-Control Studies; Female; Humans; Male; Osmolar Concentration; Reference Values; Thyroid Diseases; Transforming Growth Factor beta; Triiodothyronine; Triiodothyronine, Reverse

Because little has been published on early effects of treatment with amiodarone on thyroid function, we studied serum total and free thyroid hormone, reverse T3, and TSH levels in patients with cardiac arrhythmias during the first 10 days of treatment with a loading dose of amiodarone by iv infusion. Twenty-four patients were enrolled in the study. A standardized loading regimen for the i.v. infusion of amiodarone was used. The protocol provided the i.v. infusion of 20 mg/kg per day on day 1, the i.v. infusion of 10 mg/kg per day on day 2, then 600 mg/day per os for 7-10 days, and finally, in patients chronically treated with the drug, the dose was gradually reduced to 400-200 mg/day per os. Total and free concentrations of T4 tended to progressively and significantly increase (P < 0.0001 repeated measures ANOVA) starting from the fourth day of therapy, whereas total T3 decreased from the second day progressively (P < 0.0001) throughout the study; free T3 did not significantly change. TSH levels early and significantly (P < 0.001, by ANOVA) increased throughout the study, starting from the first day of therapy and reaching at 10 days a value 2.7 times higher than the basal value. Reverse T3 levels progressively and significantly (after 2 days of treatment) increased and paralleled the TSH values, reaching at the 10th day a value about 2 times higher than basal value. In conclusion, our data suggest that after i.v. treatment with amiodarone: 1) TSH is the first hormone to change significantly followed by reverse T3, T4, and T3; 2) the progressive fall of T3 levels reflects an inhibition of the peripheral conversion of T4 to T3; 3) the observed later increase of total and free T4 levels may be explained by a contribution of direct thyroidal stimulation by TSH and/or by a reduction in T4 clearance.

Topics: Aged; Amiodarone; Arrhythmias, Cardiac; Female; Humans; Kinetics; Male; Middle Aged; Thyroid Diseases; Thyroid Gland; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Abnormal thyroid function was shown in children with Down syndrome (DS). This study was undertaken in order to specify these anomalies.. Thyroid function of 105 children with DS aged from 3 months to 20 years was studied by evaluation of serum concentration of thyrotropin, free T4 (FT4), free T3 (FT3) and reverse T3 (rT3). Each DS child was matched to a control of the same age.. The mean concentration of thyrotropin of children with DS was increased while the mean concentration of rT3 of the DS children was significantly decreased compared with the controls, as was the ratio rT3/TSH. When DS children are split into two groups, those with and those without increased thyrotropinemia, a significant decrease in the ratio rT3/TSH appeared in DS children with increased thyrotropinemia whereas there is no difference between these two groups regarding to level of FT4, FT3, rT3 and zincemia. However, in all DS children serum zinc levels were lower than in controls. Thyrotropin levels rapidly normalized after thyroxin treatment.. One half of the children with DS have increased thyrotropinemia and all have a decreased rT3.

Topics: Adolescent; Adult; Age Determination by Skeleton; Child; Child, Preschool; Down Syndrome; Female; Humans; Infant; Male; Thyroid Diseases; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adolescent; Child; Child, Preschool; Female; Humans; Infant; Infant, Newborn; Male; Pregnancy; Radioimmunoassay; Reference Values; Thyroid Diseases; Thyroid Hormones; Triiodothyronine, Reverse

Topics: Female; Humans; Kidney Diseases; Labor, Obstetric; Liver Diseases; Pregnancy; Thyroid Diseases; Triiodothyronine, Reverse

Topics: Biopsy, Needle; Humans; Thyroglobulin; Thyroid Diseases; Thyroid Gland; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

We assessed the sensitivity, specificity, predictive value of a positive result, and efficiency of tests for total thyroxin, free thyroxin index, free thyroxin, total triiodothyronine, free triiodothyronine index, and free triiodothyronine in serum from 1619 consecutive new patients with suspected thyroid dysfunction. Multivariate discriminant analysis was also used. Free thyroxin index and free thyroxin were clearly the most sensitive indicators of hypothyroidism. In contrast, all of these tests identified hyperthyroidism with similar efficiencies. By stepwise discriminant analysis, the free thyroxin index was the most efficient test for distinguishing between euthyroidism and hyperthyroidism and between euthyroidism and hypothyroidism. The combination of tests for total thyroxin, free thyroxin index, triiodothyronine, and free triiodothyronine was optimal for separating euthyroidism, hyperthyroidism, and hypothyroidism. We conclude that the free thyroxin index, despite the introduction of newer technologies, is still the best thyroid hormone test for screening for thyroid disease.

Topics: Adult; Diagnosis, Differential; Female; Humans; Hyperthyroidism; Hypothyroidism; Male; Middle Aged; Thyroid Diseases; Thyroid Function Tests; Thyroid Hormones; Thyroxine; Thyroxine-Binding Proteins; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adolescent; Adult; Aged; Female; Humans; Male; Middle Aged; Thyroid Diseases; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

We propose a mathematical model of the human hypothalamus-anterior pituitary-thyroid system regulating basal metabolism, and practice computer simulation concerning primary thyropathy such as Graves' disease, hypothyroidism, T4-toxicosis and T3-toxicosis by use of this model. In order to throw light on properties of the system, indicial responses of the hormones, T4, T3, rT3, and TSH, and the function of the thyroid gland are computed. Medical treatments for Graves' disease and for hypothyroidism are simulated with a view to enhancing clinical significance. Performance of the simulation leads to an interesting result that when the convertion rate of blood T4 to blood T3 increases, explicit T3-toxicosis occurs, although the function of the thyroid gland is normal.

Topics: Computers; Graves Disease; Humans; Hyperthyroidism; Hypothalamo-Hypophyseal System; Hypothyroidism; Mathematics; Models, Biological; Thyroid Diseases; Thyroid Gland; Thyroid Hormones; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adolescent; Adult; Aged; Child; Humans; Kidney Failure, Chronic; Liver Cirrhosis; Middle Aged; Thyroid Diseases; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

The generation of T3 and rT3 from added nonradioactive T4 in human polymorphonuclear leucocytes was measured. The amounts of the T3 and rT3 generated were estimated by radioimmunoassay in healthy volunteers and patients suffering of thyroidal and nonthyroidal diseases. Under the incubation conditions employed an increase of in vitro generation of T3 and rT3 was observed in suspensions of hyperthyroid patients, while a significant decrease was found when leucocytes from hypothyroid patients were employed. These alterations were apparently due to either the excess or lack of thyroid hormones, respectively, since they could be restored in both cases by specific clinical treatment. Furthermore, the patients suffering from nonthyroidal illnesses showed decreased T3 generating activity in their leucocyte suspensions, while increased amounts of rT3 could be detected in the same test tube. These results showed that the leucocyte incubation system is a suitable method for investigations of the extrathyroidal metabolism of thyroid hormones in humans.

Topics: Adolescent; Adult; Humans; In Vitro Techniques; Leukocytes; Neutrophils; Radioimmunoassay; Thyroid Diseases; Thyrotropin; Thyrotropin-Releasing Hormone; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adolescent; Adult; Female; Humans; Hyperthyroidism; Hypothyroidism; Male; Middle Aged; Radioimmunoassay; Thyroid Diseases; Thyroiditis; Triiodothyronine, Reverse

Topics: Amiodarone; Benzofurans; Humans; Iodine; Thyroid Diseases; Thyroid Gland; Thyroid Hormones; Triiodothyronine, Reverse

RT3(3,3',5'-triiodothyronine) levels in amniotic fluid and T4(thyroxine), T3(triiodothyronine), rT3 and TSH(thyroid-stimulating hormone) levels in maternal and cord serum were determined simultaneously by RIA. We also determined the activities of the monodeiodination of thyroxine to rT3 in placentas. Amniotic fluid rT3 and cord serum rT3 levels decreased, but T4, T3 and TSH levels increased with advancing gestational age. The activities of the monodeiodination in placentas decreased rapidly from midgestation, preterm to term. In maternal hyperthyroidism, amniotic fluid rT3 levels were markedly elevated. Moreover, there were significant positive correlations between amniotic fluid rT3 and maternal serum rT3 (r = 0.756, p less than 0.001, n = 26) and T4(r = 0.509, p less than 0.01, n = 26) in the normal 3rd trimester. We found significant correlations between amniotic fluid rT3 and fetal thyroid function as well as the activity of the monodeiodination in placenta after 17 weeks' gestation. But we couldn't find any such correlations in the 3rd trimester. These data suggest that the amniotic fluid rT3 in the 3rd trimester was affected by maternal thyroid function as well as fetal thyroid function and the activity of the monodeiodination in placenta.

Topics: Amniotic Fluid; Female; Fetal Blood; Fetal Diseases; Gestational Age; Humans; Infant, Newborn; Maternal-Fetal Exchange; Pregnancy; Pregnancy Complications; Thyroid Diseases; Thyroid Hormones; Triiodothyronine, Reverse

Amiodarone, an iodine-containing drug used frequently in the treatment of cardiac arrhythmias and angina pectoris, has many effects on thyroid hormone metabolism, including decreasing the production of triiodothyronine (T3) and decreasing the clearance of thyroxine and reverse T3. These effects result in elevated serum thyroxine and reverse T3 concentrations and decreased serum T3 concentrations. In addition, iodine-induced hyperthyroidism or hypothyroidism may occur in patients chronically treated with amiodarone. This study is a retrospective analysis of the incidence of thyroid dysfunction in Lucca and Pisa, West Tuscany, Italy, and in Worcester, Massachusetts. Hyperthyroidism was a more frequent (9.6%) complication of amiodarone therapy in West Tuscany, where iodine intake is moderately low; hypothyroidism was more frequent (22%) in Worcester, where iodine intake is sufficient. In patients receiving chronic amiodarone therapy, clinically suspected hyperthyroidism is best confirmed by showing elevations in serum T3 or free T3 concentrations; hypothyroidism is best diagnosed by showing an elevated serum thyrotrophin concentration. Thyroid function should be carefully monitored in patients receiving amiodarone chronically, especially if they have goiter or Hashimoto's thyroiditis.

Topics: Adult; Aged; Amiodarone; Benzofurans; Female; Goiter; Heart Diseases; Humans; Hyperthyroidism; Hypothyroidism; Iodine; Italy; Long-Term Care; Male; Massachusetts; Middle Aged; Retrospective Studies; Thyroglobulin; Thyroid Diseases; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adolescent; Adult; Aged; Female; Humans; Hyperthyroidism; Hypothyroidism; Male; Middle Aged; Thyroid Diseases; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Serum thyroid hormone, thyrotropin (TSH) and thyroxine-binding globulin (TBG) concentrations, free thyroxine index values, and free thyroxine concentrations were measured at the time of admission in all 77 patients hospitalized on a medical service on four separate days. Serum thyroxine (T4) concentrations and serum free T4 index values were decreased in 19.5% and 11.7%, respectively, and increased in 3.9% and 11.7%, respectively; serum free T4 concentrations were decreased in 6.8% and increased in 5.4%. Six patients (7.8%) had increased serum TSH concentrations. Serum triiodothyronine (T3) concentrations were decreased in 26.0% and reverse triiodothyronine (rT3) concentrations were increased in 29.9%. None had manifestations of thyroid disease. These results indicate that available thyroid function tests may give misleading results in patients with nonthyroid illness and suggest that caution be exercised in diagnosing thyroid disease in hospitalized patients.

Topics: Adolescent; Adult; Aged; Female; Humans; Male; Middle Aged; Thyroid Diseases; Thyroid Function Tests; Thyrotropin; Thyroxine; Thyroxine-Binding Proteins; Triiodothyronine; Triiodothyronine, Reverse

Three phenotypically normal family members were discovered to have elevated thyroid function (T4, free T4, T3, 123I uptake), but were clinically euthyroid. Further evaluation of pituitary and peripheral indices of thyroid hormone action was consistent with the diagnosis of peripheral resistance to thyroid hormone. Basal metabolic rate, serum cholesterol, pulse wave arrival time (QKd), and serum sex hormone binding globulin levels were all normal. Serum TSH was inappropriately elevated for the degree of thyroid hormone excess, while serum alpha subunit levels were normal. TSH responses to TRH (200 micrograms) were commensurate with the basal TSH levels, and decreases in TSH were observed after T3, dexamethasone, and bromocriptine administration. Analysis of thyroid hormone binding to an extract of mononuclear leukocyte nuclei disclosed no abnormalities. The reason for these patients' resistance to thyroid hormones remains to be elucidated. The proper diagnosis of this syndrome may be difficult. Assessment of pituitary TSH secretory dynamics and peripheral indices of thyroid hormone action should be performed in all hyperthyroxinemic patients who do not have obvious symptoms and signs of thyrotoxicosis.

Topics: Adolescent; Adult; Bromocriptine; Drug Resistance; Female; Humans; Male; Pituitary Gland; Sex Hormone-Binding Globulin; Thyroid Diseases; Thyroid Function Tests; Thyroid Hormones; Thyrotropin; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Humans; Radioimmunoassay; Radionuclide Imaging; Thyroid Diseases; Thyroid Function Tests; Thyroid Gland; Thyrotropin; Thyrotropin-Releasing Hormone; Thyroxine; Thyroxine-Binding Proteins; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adult; Contraceptives, Oral; Diiodothyronines; Female; Fetal Blood; Humans; Hyperthyroidism; Hypothyroidism; Infant, Newborn; Kinetics; Male; Thyroid Diseases; Thyroidectomy; Thyronines; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adult; Female; Humans; Middle Aged; Radioimmunoassay; Thyroid Diseases; Triiodothyronine; Triiodothyronine, Reverse

Topics: Female; Humans; Pregnancy; Pregnancy Trimester, Second; Pregnancy Trimester, Third; Thyroid Diseases; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adult; Aged; Female; Glomerular Filtration Rate; Humans; Kidney; Kidney Function Tests; Male; Middle Aged; Radioimmunoassay; Thyroid Diseases; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse; Ultrafiltration

Topics: Cell Migration Inhibition; Congenital Hypothyroidism; Diagnosis, Differential; Electrophoresis; Humans; Thyroid Diseases; Triiodothyronine, Reverse

Topics: Adolescent; Adult; Humans; Infant, Newborn; Iodine; Kidney; Liver; Liver Cirrhosis; Nutrition Disorders; Thyroid Diseases; Thyroid Hormones; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adolescent; Adult; Aged; Cysts; Female; Humans; Male; Middle Aged; Parathyroid Diseases; Thyroglossal Cyst; Thyroid Diseases; Thyroid Gland; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Humans; Radioimmunoassay; Reagent Kits, Diagnostic; Thyroid Diseases; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adolescent; Adult; Aged; Female; Humans; Male; Middle Aged; Thyroid Diseases; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Humans; Radioimmunoassay; Reagent Kits, Diagnostic; Thyroid Diseases; Thyroxine; Triiodothyronine; Triiodothyronine, Reverse

Topics: Adolescent; Adult; Evaluation Studies as Topic; Female; Humans; Middle Aged; Pregnancy; Radioimmunoassay; Reagent Kits, Diagnostic; Thyroid Diseases; Triiodothyronine; Triiodothyronine, Reverse