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thyroxine (T4)

Function: - thyroid hormones increase metabolic rate of tissues - involved in regulation of growth & differentiation Compartment: - plasma - nearly all (> 99.9%) is bound one of the 3 major plasma thyroid hormone-binding proteins (thyroxine-binding globulin, prealbumin & albumin) Expression: - T4 is formed (via activity of thyroid peroxidase) & stored as an iodinated residue of thyroglobulin - normal thyroid gland makes 80 g of T4/day Pharmacology: - levothyroxine is used for treatment of hypothyroidism Pharmacokinetics: - metabolized by sulfotransferase 6B1 (SULT6B1) Laboratory: - therapeutic range for levothyroxine is determined by normalizing serum TSH in patients with intact pituitary function [3] (see hypothyroidism)

Interactions

drug interactions

Related

dextrothyroxine (Cholixin) euthyroid hyperthyroxinemia free thyroxine index (fT4I) thyroglobulin; Tg (TG) thyroid peroxidase thyroxine [T4] (free) in serum thyroxine [T4] (total) in serum thyroxine-binding globulin; Serpin A7; T4-binding globulin (SERPINA7, TBG)

Specific

levothyroxine (Synthroid, Levoxyl, Levothroid, Unithroid, Levolet, Novothyrox, Thyrotab)

General

thyroid hormone thyronine

Properties

SIZE: MW = 777 G/M MISC-INFO: elimination route LIVER

Database Correlations

PUBCHEM correlations

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. UniProt :accession Q6IMI4
  3. Medical Knowledge Self Assessment Program (MKSAP) 16, American College of Physicians, Philadelphia 2012

Component-of

thyroxine/triiodothyronine (Euthroid, Thyrolar)