Thyrotropin: A glycoprotein hormone secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Thyrotropin stimulates THYROID GLAND by increasing the iodide transport, synthesis and release of thyroid hormones (THYROXINE and TRIIODOTHYRONINE). Thyrotropin consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the pituitary glycoprotein hormones (TSH; LUTEINIZING HORMONE and FSH), but the beta subunit is unique and confers its biological specificity.Receptors, Thyrotropin: Cell surface proteins that bind pituitary THYROTROPIN (also named thyroid stimulating hormone or TSH) and trigger intracellular changes of the target cells. TSH receptors are present in the nervous system and on target cells in the thyroid gland. Autoantibodies to TSH receptors are implicated in thyroid diseases such as GRAVES DISEASE and Hashimoto disease (THYROIDITIS, AUTOIMMUNE).Thyroid Gland: A highly vascularized endocrine gland consisting of two lobes joined by a thin band of tissue with one lobe on each side of the TRACHEA. It secretes THYROID HORMONES from the follicular cells and CALCITONIN from the parafollicular cells thereby regulating METABOLISM and CALCIUM level in blood, respectively.Thyrotropin-Releasing Hormone: A tripeptide that stimulates the release of THYROTROPIN and PROLACTIN. It is synthesized by the neurons in the PARAVENTRICULAR NUCLEUS of the HYPOTHALAMUS. After being released into the pituitary portal circulation, TRH (was called TRF) stimulates the release of TSH and PRL from the ANTERIOR PITUITARY GLAND.Thyroxine: The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (MONOIODOTYROSINE) and the coupling of iodotyrosines (DIIODOTYROSINE) in the THYROGLOBULIN. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form TRIIODOTHYRONINE which exerts a broad spectrum of stimulatory effects on cell metabolism.Hypothyroidism: A syndrome that results from abnormally low secretion of THYROID HORMONES from the THYROID GLAND, leading to a decrease in BASAL METABOLIC RATE. In its most severe form, there is accumulation of MUCOPOLYSACCHARIDES in the SKIN and EDEMA, known as MYXEDEMA.Hyperthyroidism: Hypersecretion of THYROID HORMONES from the THYROID GLAND. Elevated levels of thyroid hormones increase BASAL METABOLIC RATE.Thyrotropin Alfa: A highly purified recombinant glycoprotein form of human THYROID-STIMULATING HORMONE, produced by recombinant DNA technology comprising two non-covalently linked subunits, an alpha subunit of 92 amino acid residues containing two N-linked glycosylation sites, and a beta subunit of 118 residues containing one N-linked glycosylation site. The amino acid sequence of thyrotropin alfa is identical to that of human pituitary thyroid stimulating hormone.Thyroid Function Tests: Blood tests used to evaluate the functioning of the thyroid gland.Immunoglobulins, Thyroid-Stimulating: Autoantibodies that bind to the thyroid-stimulating hormone (TSH) receptor (RECEPTORS, THYROTROPIN) on thyroid epithelial cells. The autoantibodies mimic TSH causing an unregulated production of thyroid hormones characteristic of GRAVES DISEASE.Graves Disease: A common form of hyperthyroidism with a diffuse hyperplastic GOITER. It is an autoimmune disorder that produces antibodies against the THYROID STIMULATING HORMONE RECEPTOR. These autoantibodies activate the TSH receptor, thereby stimulating the THYROID GLAND and hypersecretion of THYROID HORMONES. These autoantibodies can also affect the eyes (GRAVES OPHTHALMOPATHY) and the skin (Graves dermopathy).Triiodothyronine: A T3 thyroid hormone normally synthesized and secreted by the thyroid gland in much smaller quantities than thyroxine (T4). Most T3 is derived from peripheral monodeiodination of T4 at the 5' position of the outer ring of the iodothyronine nucleus. The hormone finally delivered and used by the tissues is mainly T3.Congenital Hypothyroidism: A condition in infancy or early childhood due to an in-utero deficiency of THYROID HORMONES that can be caused by genetic or environmental factors, such as thyroid dysgenesis or HYPOTHYROIDISM in infants of mothers treated with THIOURACIL during pregnancy. Endemic cretinism is the result of iodine deficiency. Clinical symptoms include severe MENTAL RETARDATION, impaired skeletal development, short stature, and MYXEDEMA.Thyrotropin, beta Subunit: The beta subunit of thyroid stimulating hormone, thyrotropin. It is a 112-amino acid glycopolypeptide of about 16 kD. Full biological activity of TSH requires the non-covalently bound heterodimers of an alpha and a beta subunit.Thyroid Hormones: Natural hormones secreted by the THYROID GLAND, such as THYROXINE, and their synthetic analogs.ThyroglobulinThyroid Diseases: Pathological processes involving the THYROID GLAND.Radioimmunoassay: Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation.Iodine: A nonmetallic element of the halogen group that is represented by the atomic symbol I, atomic number 53, and atomic weight of 126.90. It is a nutritionally essential element, especially important in thyroid hormone synthesis. In solution, it has anti-infective properties and is used topically.Triiodothyronine, Reverse: A metabolite of THYROXINE, formed by the peripheral enzymatic monodeiodination of T4 at the 5 position of the inner ring of the iodothyronine nucleus.Iodide Peroxidase: A hemeprotein that catalyzes the oxidation of the iodide radical to iodine with the subsequent iodination of many organic compounds, particularly proteins. EC 220.127.116.11.Pituitary Hormones, Anterior: Hormones secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Structurally, they include polypeptide, protein, and glycoprotein molecules.Iodides: Inorganic binary compounds of iodine or the I- ion.Cyclic AMP: An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.Exophthalmos: Abnormal protrusion of both eyes; may be caused by endocrine gland malfunction, malignancy, injury, or paralysis of the extrinsic muscles of the eye.Goiter: Enlargement of the THYROID GLAND that may increase from about 20 grams to hundreds of grams in human adults. Goiter is observed in individuals with normal thyroid function (euthyroidism), thyroid deficiency (HYPOTHYROIDISM), or hormone overproduction (HYPERTHYROIDISM). Goiter may be congenital or acquired, sporadic or endemic (GOITER, ENDEMIC).Pituitary Gland: A small, unpaired gland situated in the SELLA TURCICA. It is connected to the HYPOTHALAMUS by a short stalk which is called the INFUNDIBULUM.Pituitary Gland, Anterior: The anterior glandular lobe of the pituitary gland, also known as the adenohypophysis. It secretes the ADENOHYPOPHYSEAL HORMONES that regulate vital functions such as GROWTH; METABOLISM; and REPRODUCTION.Reagent Kits, Diagnostic: Commercially prepared reagent sets, with accessory devices, containing all of the major components and literature necessary to perform one or more designated diagnostic tests or procedures. They may be for laboratory or personal use.Propylthiouracil: A thiourea antithyroid agent. Propythiouracil inhibits the synthesis of thyroxine and inhibits the peripheral conversion of throxine to tri-iodothyronine. It is used in the treatment of hyperthyroidism. (From Martindale, The Extra Pharmacopeoia, 30th ed, p534)Immunoassay: A technique using antibodies for identifying or quantifying a substance. Usually the substance being studied serves as antigen both in antibody production and in measurement of antibody by the test substance.Graves Ophthalmopathy: An autoimmune disorder of the EYE, occurring in patients with Graves disease. Subtypes include congestive (inflammation of the orbital connective tissue), myopathic (swelling and dysfunction of the extraocular muscles), and mixed congestive-myopathic ophthalmopathy.Thyrotoxicosis: A hypermetabolic syndrome caused by excess THYROID HORMONES which may come from endogenous or exogenous sources. The endogenous source of hormone may be thyroid HYPERPLASIA; THYROID NEOPLASMS; or hormone-producing extrathyroidal tissue. Thyrotoxicosis is characterized by NERVOUSNESS; TACHYCARDIA; FATIGUE; WEIGHT LOSS; heat intolerance; and excessive SWEATING.Prolactin: A lactogenic hormone secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). It is a polypeptide of approximately 23 kD. Besides its major action on lactation, in some species prolactin exerts effects on reproduction, maternal behavior, fat metabolism, immunomodulation and osmoregulation. Prolactin receptors are present in the mammary gland, hypothalamus, liver, ovary, testis, and prostate.Harderian Gland: A sebaceous gland that, in some animals, acts as an accessory to the lacrimal gland. The harderian gland excretes fluid that facilitates movement of the third eyelid.Glycoprotein Hormones, alpha Subunit: The alpha chain of pituitary glycoprotein hormones (THYROTROPIN; FOLLICLE STIMULATING HORMONE; LUTEINIZING HORMONE) and the placental CHORIONIC GONADOTROPIN. Within a species, the alpha subunits of these four hormones are identical; the distinct functional characteristics of these glycoprotein hormones are determined by the unique beta subunits. Both subunits, the non-covalently bound heterodimers, are required for full biologic activity.Receptors, Thyrotropin-Releasing Hormone: Cell surface receptors that bind thyrotropin releasing hormone (TRH) with high affinity and trigger intracellular changes which influence the behavior of cells. Activated TRH receptors in the anterior pituitary stimulate the release of thyrotropin (thyroid stimulating hormone, TSH); TRH receptors on neurons mediate neurotransmission by TRH.Thyroxine-Binding Proteins: Blood proteins that bind to THYROID HORMONES such as THYROXINE and transport them throughout the circulatory system.Thyroid Neoplasms: Tumors or cancer of the THYROID GLAND.Carbimazole: An imidazole antithyroid agent. Carbimazole is metabolized to METHIMAZOLE, which is responsible for the antithyroid activity.Thyroiditis, Autoimmune: Inflammatory disease of the THYROID GLAND due to autoimmune responses leading to lymphocytic infiltration of the gland. It is characterized by the presence of circulating thyroid antigen-specific T-CELLS and thyroid AUTOANTIBODIES. The clinical signs can range from HYPOTHYROIDISM to THYROTOXICOSIS depending on the type of autoimmune thyroiditis.Antithyroid Agents: Agents that are used to treat hyperthyroidism by reducing the excessive production of thyroid hormones.Pyrrolidonecarboxylic Acid: A cyclized derivative of L-GLUTAMIC ACID. Elevated blood levels may be associated with problems of GLUTAMINE or GLUTATHIONE metabolism.Autoantibodies: Antibodies that react with self-antigens (AUTOANTIGENS) of the organism that produced them.Myxedema: A condition characterized by a dry, waxy type of swelling (EDEMA) with abnormal deposits of MUCOPOLYSACCHARIDES in the SKIN and other tissues. It is caused by a deficiency of THYROID HORMONES. The skin becomes puffy around the eyes and on the cheeks. The face is dull and expressionless with thickened nose and lips.Iodine Radioisotopes: Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.Pituitary Neoplasms: Neoplasms which arise from or metastasize to the PITUITARY GLAND. The majority of pituitary neoplasms are adenomas, which are divided into non-secreting and secreting forms. Hormone producing forms are further classified by the type of hormone they secrete. Pituitary adenomas may also be characterized by their staining properties (see ADENOMA, BASOPHIL; ADENOMA, ACIDOPHIL; and ADENOMA, CHROMOPHOBE). Pituitary tumors may compress adjacent structures, including the HYPOTHALAMUS, several CRANIAL NERVES, and the OPTIC CHIASM. Chiasmal compression may result in bitemporal HEMIANOPSIA.Goiter, Nodular: An enlarged THYROID GLAND containing multiple nodules (THYROID NODULE), usually resulting from recurrent thyroid HYPERPLASIA and involution over many years to produce the irregular enlargement. Multinodular goiters may be nontoxic or may induce THYROTOXICOSIS.Methimazole: A thioureylene antithyroid agent that inhibits the formation of thyroid hormones by interfering with the incorporation of iodine into tyrosyl residues of thyroglobulin. This is done by interfering with the oxidation of iodide ion and iodotyrosyl groups through inhibition of the peroxidase enzyme.Potassium Iodide: An inorganic compound that is used as a source of iodine in thyrotoxic crisis and in the preparation of thyrotoxic patients for thyroidectomy. (From Dorland, 27th ed)Thyroidectomy: Surgical removal of the thyroid gland. (Dorland, 28th ed)Transcription Factor Pit-1: A POU domain factor that regulates expression of GROWTH HORMONE; PROLACTIN; and THYROTROPIN-BETA in the ANTERIOR PITUITARY GLAND.Growth Hormone: A polypeptide that is secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Growth hormone, also known as somatotropin, stimulates mitosis, cell differentiation and cell growth. Species-specific growth hormones have been synthesized.Thyroiditis: Inflammatory diseases of the THYROID GLAND. Thyroiditis can be classified into acute (THYROIDITIS, SUPPURATIVE), subacute (granulomatous and lymphocytic), chronic fibrous (Riedel's), chronic lymphocytic (HASHIMOTO DISEASE), transient (POSTPARTUM THYROIDITIS), and other AUTOIMMUNE THYROIDITIS subtypes.Adenylate Cyclase: An enzyme of the lyase class that catalyzes the formation of CYCLIC AMP and pyrophosphate from ATP. EC 18.104.22.168.Euthyroid Sick Syndromes: Conditions of abnormal THYROID HORMONES release in patients with apparently normal THYROID GLAND during severe systemic illness, physical TRAUMA, and psychiatric disturbances. It can be caused by the loss of endogenous hypothalamic input or by exogenous drug effects. The most common abnormality results in low T3 THYROID HORMONE with progressive decrease in THYROXINE; (T4) and TSH. Elevated T4 with normal T3 may be seen in diseases in which THYROXINE-BINDING GLOBULIN synthesis and release are increased.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Orbit: Bony cavity that holds the eyeball and its associated tissues and appendages.Iopanoic Acid: Radiopaque medium used as diagnostic aid.PaperReceptors, Cell Surface: Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.Hypopituitarism: Diminution or cessation of secretion of one or more hormones from the anterior pituitary gland (including LH; FOLLICLE STIMULATING HORMONE; SOMATOTROPIN; and CORTICOTROPIN). This may result from surgical or radiation ablation, non-secretory PITUITARY NEOPLASMS, metastatic tumors, infarction, PITUITARY APOPLEXY, infiltrative or granulomatous processes, and other conditions.Sodium Iodide: A compound forming white, odorless deliquescent crystals and used as iodine supplement, expectorant or in its radioactive (I-131) form as an diagnostic aid, particularly for thyroid function tests.Pituitary Function Tests: Examinations that evaluate functions of the pituitary gland.Microchemistry: The development and use of techniques and equipment to study or perform chemical reactions, with small quantities of materials, frequently less than a milligram or a milliliter.Bucladesine: A cyclic nucleotide derivative that mimics the action of endogenous CYCLIC AMP and is capable of permeating the cell membrane. It has vasodilator properties and is used as a cardiac stimulant. (From Merck Index, 11th ed)Thyroiditis, Subacute: Spontaneously remitting inflammatory condition of the THYROID GLAND, characterized by FEVER; MUSCLE WEAKNESS; SORE THROAT; severe thyroid PAIN; and an enlarged damaged gland containing GIANT CELLS. The disease frequently follows a viral infection.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Kinetics: The rate dynamics in chemical or physical systems.CHO Cells: CELL LINE derived from the ovary of the Chinese hamster, Cricetulus griseus (CRICETULUS). The species is a favorite for cytogenetic studies because of its small chromosome number. The cell line has provided model systems for the study of genetic alterations in cultured mammalian cells.Chorionic Gonadotropin: A gonadotropic glycoprotein hormone produced primarily by the PLACENTA. Similar to the pituitary LUTEINIZING HORMONE in structure and function, chorionic gonadotropin is involved in maintaining the CORPUS LUTEUM during pregnancy. CG consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is virtually identical to the alpha subunits of the three pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity (CHORIONIC GONADOTROPIN, BETA SUBUNIT, HUMAN).Reference Values: The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.Ablation Techniques: Removal of tissue by vaporization, abrasion, or destruction. Methods used include heating tissue by hot liquids or microwave thermal heating, freezing (CRYOABLATION), chemical ablation, and photoablation with LASERS.Luteinizing Hormone: A major gonadotropin secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Luteinizing hormone regulates steroid production by the interstitial cells of the TESTIS and the OVARY. The preovulatory LUTEINIZING HORMONE surge in females induces OVULATION, and subsequent LUTEINIZATION of the follicle. LUTEINIZING HORMONE consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the three pituitary glycoprotein hormones (TSH, LH and FSH), but the beta subunit is unique and confers its biological specificity.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Receptors, LH: Those protein complexes or molecular sites on the surfaces and cytoplasm of gonadal cells that bind luteinizing or chorionic gonadotropic hormones and thereby cause the gonadal cells to synthesize and secrete sex steroids. The hormone-receptor complex is internalized from the plasma membrane and initiates steroid synthesis.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Hyperthyroxinemia: Abnormally elevated THYROXINE level in the BLOOD.
Thyrotropic cellFollicular cellTRH stimulation test: Prior to the availability of sensitive TSH assays, thyrotropin releasing hormone (TRH)HypothyroidismHyperthyroidismSymptoms and signs of Graves' disease: Virtually all the symptoms and signs of Graves' disease result from the direct and indirect effects of hyperthyroidism, with exceptions being Graves' ophthalmopathy, goitre and pretibial myxedema (which are caused by the autoimmune processes of Graves' disease). These clinical manifestations are dramatic and involve virtually every system in the body.Reverse triiodothyronineCongenital hypothyroidismThyroid hormone: The thyroid hormones, triiodothyronine (T3) and its prohormone, thyroxine (T4), are tyrosine-based hormones produced by the thyroid gland that are primarily responsible for regulation of metabolism. T3 and T4 are partially composed of iodine (see molecular model).Thyroglobulin: Thyroglobulin (Tg) is a 660 kDa, dimeric protein produced by the follicular cells of the thyroid and used entirely within the thyroid gland. Thyroglobulin protein accounts for approximately half of the protein content of the thyroid gland.Iodine deficiencyIodothyronine deiodinase: Iodothyronine deiodinases ( and ) are a subfamily of deiodinase enzymes important in the activation and deactivation of thyroid hormones. Thyroxine (T4), the precursor of 3,5,3’-triiodothyronine (T3) is transformed into T3 by deiodinase activity.TriiodideCrosstalk (biology): Biological crosstalk refers to instances in which one or more components of one signal transduction pathway affects another. This can be achieved through a number of ways with the most common form being crosstalk between proteins of signalling cascades.ExophthalmosGoitreAnterior pituitary: A major organ of the endocrine system, the anterior pituitary (also called the adenohypophysis or pars anterior), is the glandular, anterior lobe that together with the posterior lobe (posterior pituitary, or the neurohypophysis) makes up the pituitary gland (hypophysis). The anterior pituitary regulates several physiological processes including stress, growth, reproduction and lactation.Bioline Reagents: Bioline Reagents is a primary manufacturer and developerBioline: The PCR Company | Company Profile of a wide range of specialised molecular biology products for the life science industry and research markets. It manufactures reagents including ultra-pure nucleotides, DNA polymerases and mixes, DNA markers, competent cells, products for RNA analysis and other general reagents for molecular biology.PropylthiouracilImmunoassay: An immunoassay is a biochemical test that measures the presence or concentration of a macromolecule in a solution through the use of an antibody or immunoglobulin. The macromolecule detected by the immunoassay is often referred to as an "analyte" and is in many cases a protein.Infiltrative ophthalmopathy: Infiltrative ophthalmopathy is found in Graves disease and resembles exophthalmos, except that the blurry or double vision is acquired because of weakness in the ocular muscles of the eye. In addition, there is no known correlation with the patient's thyroid levels.Prolactin cellHarderian gland: The Harderian gland is a gland found within the eye's orbit which occurs in tetrapods (reptiles, amphibians, birds and mammals) that possess a nictitating membrane.Thyroid cancerAutoimmune thyroiditisHigh anion gap metabolic acidosisAutoantibody: An autoantibody is an antibody (a type of protein) produced by the immune system that is directed against one or more of the individual's own proteins. Many autoimmune diseases, (notably lupus erythematosus), are caused by such autoantibodies.MyxedemaPituitary adenomaToxic nodular goiterLeRoy ApkerThyroidectomySomatotropic cellRiedel's thyroiditisCyclase-associated protein family: In molecular biology, the cyclase-associated protein family (CAP) is a family of highly conserved actin-binding proteins present in a wide range of organisms including yeast, flies, plants, and mammals. CAPs are multifunctional proteins that contain several structural domains.Euthyroid sick syndromeBeef cattle: Beef cattle are cattle raised for meat production (as distinguished from dairy cattle, used for milk production). The meat of adult cattle is known as beef.Superior orbital fissure: The superior orbital fissure is a foramen in the skull, although strictly it is more of a cleft, lying between the lesser and greater wings of the sphenoid bone.Iopanoic acidSuperabsorbent polymer: Superabsorbent polymers (SAPs) (also called slush powder) are polymers that can absorb and retain extremely large amounts of a liquid relative to their own mass. Horie, K, et.Sheehan's syndromeBucladesineSubacute thyroiditisCell membraneBurst kinetics: Burst kinetics is a form of enzyme kinetics that refers to an initial high velocity of enzymatic turnover when adding enzyme to substrate. This initial period of high velocity product formation is referred to as the "Burst Phase".Equine chorionic gonadotropin: Equine chorionic gonadotropin (eCG) is a gonadotropic hormone produced in the chorion of pregnant mares. Most commonly called pregnant mare's serum gonadotropin (PMSG) in the past, the hormone is commonly used in concert with progestogen to induce ovulation in livestock prior to artificial insemination.Cell ablation: Cell ablation (also known as tissue ablation) is a biotechnological tool for studying cell lineage and/or function and is a form of ablation. The process consists of selectively destroying one or multiple cells in a given organism by any chosen means.Kennel clubGs alpha subunit: The Gs alpha subunit (Gαs, Gsα, or Gs protein) is a heterotrimeric G protein subunit that activates the cAMP-dependent pathway by activating adenylyl cyclase. A mnemonic for remembering this subunit is to look at the first letters in each word (Gαs = Adenylate Syclase).Coles PhillipsFamilial dysalbuminemic hyperthyroxinemia: Familial dysalbuminemic hyperthyroxinemia is a type of hyperthyroxinemia associated with mutations in the human serum albumin gene.
(1/2714) Measurement of serum TSH in the investigation of patients presenting with thyroid enlargement.
In otherwise euthyroid patients presenting with thyroid enlargement, reduction in serum thyrotrophin (TSH) concentrations measured in a sensitive assay may be a marker of thyroid autonomy and may therefore indicate a benign underlying pathology. We investigated prospectively a cohort of 467 subjects presenting consecutively to our thyroid clinic with nodular or diffuse enlargement of the thyroid. Subjects were divided into those with normal (0.4-5.5 mU/l), low but detectable (0.1-0.39 mU/l) or undetectable (< 0.1 mU/l) serum TSH concentrations. The final pathological diagnosis was defined by fine-needle aspiration cytology and clinical follow-up of at least 2 years or by fine-needle aspiration cytology and histology following surgical treatment. Serum TSH concentrations below normal were found in 75 patients (16.1%), those with low serum TSH results having higher mean free T4 concentrations, were older and were more likely to be female. In those with undetectable serum TSH, no patient had a diagnosis of thyroid neoplasia and in those with low but detectable TSH, thyroid neoplasms were diagnosed in two patients (3.4%). In those with normal serum TSH, 12.0% had a final diagnosis of thyroid neoplasm (p = 0.013). Overall, thyroid malignancy was found in one patient (1.3%) of those with a serum TSH measurement below the normal range and 6.9% of those with normal serum TSH (p < 0.06). Reduction in serum TSH at presentation may identify a group which requires less intensive investigation and follow-up than those without biochemical evidence of thyroid autonomy. (+info)
(2/2714) Growth hormone-releasing peptide-2 infusion synchronizes growth hormone, thyrotrophin and prolactin release in prolonged critical illness.
OBJECTIVE: During prolonged critical illness, nocturnal pulsatile secretion of GH, TSH and prolactin (PRL) is uniformly reduced but remains responsive to the continuous infusion of GH secretagogues and TRH. Whether such (pertinent) secretagogues would synchronize pituitary secretion of GH, TSH and/or PRL is not known. DESIGN AND METHODS: We explored temporal coupling among GH, TSH and PRL release by calculating cross-correlation among GH, TSH and PRL serum concentration profiles in 86 time series obtained from prolonged critically ill patients by nocturnal blood sampling every 20 min for 9 h during 21-h infusions of either placebo (n=22), GHRH (1 microg/kg/h; n=10), GH-releasing peptide-2 (GHRP-2; 1 microg/kg/h; n=28), TRH (1 microg/kg/h; n=8) or combinations of these agonists (n=8). RESULTS: The normal synchrony among GH, TSH and PRL was absent during placebo delivery. Infusion of GHRP-2, but not GHRH or TRH, markedly synchronized serum profiles of GH, TSH and PRL (all P< or =0.007). After addition of GHRH and TRH to the infusion of GHRP-2, only the synchrony between GH and PRL was maintained (P=0.003 for GHRH + GHRP-2 and P=0.006 for TRH + GHRH + GHRP-2), and was more marked than with GHRP-2 infusion alone (P=0.0006 by ANOVA). CONCLUSIONS: The nocturnal GH, TSH and PRL secretory patterns during prolonged critical illness are herewith further characterized to include loss of synchrony among GH, TSH and PRL release. The synchronizing effect of an exogenous GHRP-2 drive, but not of GHRH or TRH, suggests that the presumed endogenous GHRP-like ligand may participate in the orchestration of coordinated anterior pituitary hormone release. (+info)
(3/2714) Insulin and TSH promote growth in size of PC Cl3 rat thyroid cells, possibly via a pathway different from DNA synthesis: comparison with FRTL-5 cells.
In the rat thyroid cell lines PC Cl3, FRTL- 5 and WRT, proliferation is mainly regulated by insulin or IGF, and TSH. However, the mechanism regulating cell mass doubling prior to division is still unknown. Our laboratory has shown that in dog thyroid cells insulin promotes growth in size while TSH in the presence of insulin triggers DNA replication. In the absence of insulin, TSH has no effect on cell growth. In this report we investigated insulin action on both cell mass and DNA synthesis and its modulation by TSH and insulin in PC Cl3 and FRTL-5 cells. In PC Cl3 cells, insulin activated not only DNA synthesis but also protein synthesis and accumulation. Although TSH potentiated the stimulation of DNA synthesis induced by insulin, enhancement of protein synthesis by both agents was additive. All TSH effects were reproduced by forskolin. Similar effects were also obtained in FRTL-5 cells. This suggests that insulin and TSH, via cAMP, modulate both growth in size and DNA replication in these cell lines. Lovastatin, which blocks 3-hydroxy-3-methylglutaryl coenzyme A reductase, decreased the induction of DNA synthesis, but not of protein synthesis induced by insulin or TSH in PC Cl3 cells. In FRTL-5 cells, lovastatin reduced protein and DNA synthesis stimulated by insulin but not TSH-induced protein synthesis. Taking these data together, we propose that insulin and/or TSH both modulate cell mass doubling and DNA synthesis in these cell lines, presumably via different pathways, and that there are at least two pathways which regulate growth in size in FRTL-5 thyroid cells: one triggered by insulin, which is lovastatin sensitive, and the other activated by TSH, which is not sensitive to lovastatin. (+info)
(4/2714) Development of a thyroid function strategy for general practice.
A study was carried out to investigate a thyroid stimulating hormone (TSH) frontline strategy that could potentially result in a more straightforward interpretation of thyroid function tests, a reduction in the number of inappropriate referrals to medical outpatients, an improvement in the 'turnaround time' of results, and a reduction in the number of unnecessary tests carried out, thereby reducing costs. (+info)
(5/2714) Polarized targeting of epithelial cell proteins in thyrocytes and MDCK cells.
Polarized trafficking signals may be interpreted differently in different cell types. In this study, we have compared the polarized trafficking of different proteins expressed endogenously in primary porcine thyroid epithelial cells to similar proteins expressed in MDCK cells. As in MDCK cells, NH4Cl treatment of filter-grown thyrocytes caused mis-sorted soluble proteins to exhibit enhanced secretion to the apical medium. In independent studies, thrombospondin 1 (a thyroid basolaterally secreted protein) was secreted basolaterally from MDCK cells. Likewise, the 5'-deiodinase (a thyroid basolateral membrane protein) encoded by the DIO1 gene was also distributed basolaterally in transfected MDCK cells. Consistent with previous reports, when the secretion of human growth hormone (an unglycosylated regulated secretory protein) was examined from transfected MDCK cells, the release was nonpolarized. However, transfected thyrocytes secreted growth hormone apically in a manner dependent upon zinc addition. Moreover, two additional regulated secretory proteins expressed in thyrocytes, thyroglobulin (the major endogenous glycoprotein) and parathyroid hormone (an unglycosylated protein expressed transiently), were secreted apically even in the absence of zinc. We hypothesize that while cellular mechanisms for interpreting polarity signals are generally similar between thyrocytes and MDCK cells, thyrocytes allow for specialized packaging of regulated secretory proteins for apical delivery, which does not require glycosylation but may involve availability of certain ions as well as appropriate intracellular compartmentation. (+info)
(6/2714) Biological activities of tyrosine-containing somatostatin analogs on inhibition of secretion of thyrotropin and growth hormone.
The following five tyrosine-containing analogs of somatostatin (GIF) were synthesized by the solid-phase method: Tyr-GIF: [Tyr6]-GIF; [Tyr7]-GIF; [Tyr8]-GIF; [Tyr11]-GIF. These analogs except [Tyr8]-GIF were demonstrated to possess almost the same potency to inhibit thyrotropin release stimulated by thyrotropin-releasing hormone as that of synthesized GIF in vivo. [Tyr8]-GIF had potencies less than 0.5% of GIF. They also had the activity to inhibit Nembutal-induced growth hormone rise. The structure-activity relationship and availability of these analogs for radioimmunoassay were discussed. (+info)
(7/2714) Reverse triiodothyronine, thyroid hormone, and thyrotrophin concentrations in placental cord blood.
Reverse triiodothyronine (rT3), triiodothyronine (T3), thyroxine (T4), thyroxine binding globulin (TBG), and thyrotrophin (TSH) were measured in sera from placental cord blood in an unselected series of 272 deliveries. In this series the concentrations of rT3 (mean 3.33 nmol/l, 95% confidence limits 1.6--7.0 nmol/l), were log normally distributed and did not overlap the adult normal range (0.11--0.44 nmol/l). There were no correlations between the cord blood concentrations of rT3, T3, T4, and TSH. The cord serum rT3 concentration was not influenced by maturity, birth-weight, or neonatal risk factors, whereas these factors did affect the concentrations of T3, T4, AND TBG. There is no arteriovenous rT3 concentration difference across the placenta, therefore the cord rT3 reflects the systemic rT3 concentration in the baby at birth. As rT3 in the neonate largely, if not entirely, derives from thyroxine from the fetal thyroid, measurement of the cord rT3 concentration may be a good immediate screening test for neonatal hypothyroidism. (+info)
(8/2714) Central hypothyroidism associated with retinoid X receptor-selective ligands.
BACKGROUND: The occurrence of symptomatic central hypothyroidism (characterized by low serum thyrotropin and thyroxine concentrations) in a patient with cutaneous T-cell lymphoma during therapy with the retinoid X receptor-selective ligand bexarotene led us to hypothesize that such ligands could reversibly suppress thyrotropin production by a thyroid hormone-independent mechanism and thus cause central hypothyroidism. METHODS: We evaluated thyroid function in 27 patients with cutaneous T-cell lymphoma who were enrolled in trials of high-dose oral bexarotene at one institution. In addition, we evaluated the in vitro effect of triiodothyronine, 9-cis-retinoic acid, and the retinoid X receptor-selective ligand LGD346 on the activity of the thyrotropin beta-subunit gene promoter. RESULTS: The mean serum thyrotropin concentration declined from 2.2 mU per liter at base line to 0.05 mU per liter during treatment with bexarotene (P<0.001), and the mean serum free thyroxine concentration declined from 1.0 ng per deciliter (12.9 pmol per liter) at base line to 0.45 ng per deciliter (5.8 pmol per liter) (P<0.001) during treatment. The degree of suppression of thyrotropin secretion tended to be greater in patients treated with higher doses of bexarotene (>300 mg per square meter of body-surface area per day) and in those with a history of treatment with interferon alfa. Nineteen patients had symptoms or signs of hypothyroidism, particularly fatigue and cold intolerance. The symptoms improved after the initiation of thyroxine therapy, and all patients became euthyroid after treatment with bexarotene was stopped. In vitro, LGD346 suppressed the activity of the thyrotropin beta-subunit gene promoter in thyrotrophs by as much as 50 percent, an effect similar to that of triiodothyronine and 9-cis-retinoic acid. CONCLUSIONS: Hypothyroidism may develop in patients with cutaneous T-cell lymphoma who are treated with high-dose bexarotene, most likely because the retinoid X receptor-selective ligand suppresses thyrotropin secretion. (+info)