Endocrinology Book

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ThyroxineAka: Free T4, T4

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  1. See Also
    1. Thyroxine Replacement
    2. Hypothyroidism
    3. Hyperthyroidism
  2. Indication
    1. Evaluation of Thyroid Function
    2. Combined with Thyroid Stimulating Hormone (TSH)
      1. Together most accurate assessment of Thyroid status
  3. Normal
    1. Thyroxine (T4): 4-12 ug/dl
    2. Free Thyroxine (Free T4): 0.7 - 1.9 ng/dl
  4. Measurement
    1. Radioimmunoassay measures bound serum Thyroxine (T4)
    2. Free Thyroxine (free T4) measures only active T4
      1. Not affected by Thyroid Binding Globulin (TBG)
      2. Free Thyroxine (Free T4) represents 0.03% of total T4
  5. Increased Thyroxine or Free T4
    1. Grave's Disease
    2. Toxic Multinodular Goiter
    3. Toxic adenoma
    4. Iatrogenic/factitious
    5. Transient Hyperthyroidism
      1. Subacute Thyroiditis,
      2. Hashimoto's Thyroiditis
    6. Rarely
      1. Hyperthyroid secondary to pituitary disease
      2. Thyroid Cancer
      3. Amiodarone
  6. Decreased Thyroxine or Free T4
    1. Primary Hypothyroidism
      1. Hashimoto's Thyroiditis
      2. Idiopathic Myxedema
      3. Previous treatment of Hyperthyroidism
      4. Subacute Thyroiditis
      5. Prior neck radiotherapy
      6. Iodine deficiency or excess
      7. Congenital
      8. Medications
        1. Lithium
        2. PAS
        3. Sulfonamides
        4. Phenylbutazone
        5. Amiodarone
        6. Thiourea
    2. Secondary Hypothyroidism
      1. Pituitary dysfunction
    3. Tertiary Hypothyroidism
      1. Hypothalamic disease
    4. Very rare
      1. Tissue resistance to Thyroid hormone

Thyroxine (C0040165)

Definition (MSH)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.
Definition (CSP)tetraiodothyronine (T4); major hormone elaborated by the thyroid gland follicular cells; increases the rate of cell metabolism, essential for central nervous system maturation, and regulates a number of other functions.
Definition (PDQ)A hormone synthesized and secreted by the thyroid gland containing four iodine atoms and is converted to triiodothyronine (T3) in the body, influencing metabolism and organ function. Check for "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=528273&idtype=1" active clinical trials or "http://www.cancer.gov/Search/ClinicalTrialsLink.aspx?id=528273&idtype=1&closed=1" closed clinical trials using this agent. ("http://nciterms.nci.nih.gov:80/NCIBrowser/ConceptReport.jsp?dictionary=NCI_Thesaurus&code=C2302" NCI Thesaurus)
Definition (NCI)A hormone synthesized and secreted by the thyroid gland containing four iodine atoms and is converted to triiodothyronine (T3) in the body, influencing metabolism and organ function.
ConceptsAmino Acid, Peptide, or Protein (T116) , Pharmacologic Substance (T121) , Hormone (T125)
MSHD013974
EnglishL Thyroxine, L-Thyroxine, Levothyroxine, LEVOTHYROXINE PREPARATION, T AAB THYROID HORMONE 004, T<sub>4</sub>, T<sub>4</sub> preparation, T>4<, T>4< preparation, T4, T4 - Thyroxine, T4 preparation, T4 Thyroid Hormone, Tetraiodothyronine preparation, THROXINE L, Thyroxin, Thyroxine, Thyroxine preparation, Thyroxine product, Total thyroxine, TT4 - Total thyroxine
Spanishpreparado con tetrayodotironina, preparado de T>4, preparado de tetrayodotironina, preparado de tiroxina, tiroxina
Parent ConceptsAmine hormone (C0312440), Thyroid Hormones (C0040135), Amino Acids, Aromatic (C0301713), Amino Acids, Cyclic (C0002522), Thyroxine (C0040165), [DX900] DIAGNOSTICS, OTHER (C0973537), [HS851] THYROID SUPPLEMENTS (C0973568), Thyroid preparation (C0279175)
SourcesAOD, CSP, LCH, LNC, MSH, MTH, NCI, NDFRT, PDQ, RXNORM, SCTSPA, SNOMEDCT, USPMG, VANDF
Derived from the NIH UMLS (Unified Medical Language System)



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