Thyroid Pharmacology and Physiology

Chapter 24:  Thyroid and Antithyroid Drugs

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Thyroid Physiology and Pharmacology

  • Receptors:

  • Iodide:

  • Greenspan, F.S., and Dong, B. J.. Histamine, Thyroid and Antithyroid Drugs, in Basic and Clinical Pharmacology, (Katzung, B. G., ed) Appleton-Lange, 1998, pp 619-633.

    Wartofsky, L., Diseases of the Thyroid, In Harrison's Principles of Internal Medicine 14th edition, (Isselbacher, K.J., Braunwald, E., Wilson, J.D., Martin, J.B., Fauci, A.S. and Kasper, D.L., eds) McGraw-Hill, Inc (Health Professions Division), 1998, pp 2012-2034

    Thyroid Hormones

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    Thyroid Hormone Effects*

    Physiological system

    Hyperthyroidism (thyrotoxicosis)

    Hypothyroidism

    skin --appendages

    warm, moist skin; sweating; fine, thin hair; Plumber's nails; pretibial dermopathy (Graves' disease)

    pale, cool, puffy skin; brittle hair and nails

    Eyes, face

    Upper lid retraction (wide stare); periorbital edema; exophthalmos, diplopia (Graves' disease)

    Eyelid drooping; periorbital edema; puffy, nonpitting facies; large tongue

    Cardiovascular

    decreased peripheral resistance, increased cardiac output, stroke volume, heart rate, pulse pressure; congestive heart failure (high-output); increased contractility,. arrhythmogenic; angina

    increased peripheral resistance, decreased cardiac output, stroke volume, heart rate, pulse pressure; congestive heart failure (low output); bradycardia (low voltage ECG with prolonged PR interval, flat T wave); pericardial effusion

    Respiratory

    dyspnea; reduced vital capacity

    hypoventilation (CO2 retention) pleural effusions

    Gastrointestinal

    increased appetite; increased bowel movement frequency; hypoproteinemia

    decreased appetite, decreased bowel movement frequency; ascites

    CNS

    Nervousness, hyperkinesia, variable emotional states

    lethargy, neuropathy

    Musculoskeletal

    Weakness; fatigue; hypercalcemia, osteoporosis, increased deep tendon reflex

    muscle fatigue, reduced deep tendon reflex, increased alkaline phosphatase, LDH, AST

    Renal

    Increased renal blood flow; increased GFR; mild polyuria

    Decreased renal blood flow; decreased GFR; reduced water excretion

    Hematopoietic

    anemia (increased RBC turnover); increased erythropoiesis

    anemia (decrease production rate, decreased iron absorption, decreased folate acid absorption, autoimmune pernicious anemia),decreased erythropoiesis

    Reproductive

    decreased fertility; menstrual irregularity; enhanced gonadal steroid metabolism

    infertility;hypermenorrhea, decreased libido; impotence, decreased gonadal steroid metabolism

    Metabolic

    increased basal rate; negative nitrogen balance, hyperglycemia; increased free fatty acids, decreased cholesterol and triglycerides; increased hormone degradation; increased requirement for fat-and water-soluble vitamins; enhanced drug detoxification

    decreased basal rate; delayed insulin degradation, with increased sensitivity; enhanced cholesterol and triglyceride levels; decreased hormone degradation; decreased requirements for fat-and water-soluble vitamins; decreased drug detoxification.

    * * Adapted from Table 38-4, Greenspan, F.S., and Dong, B. J.. Histamine, Thyroid and Antithyroid Drugs, in Basic and Clinical Pharmacology, (Katzung, B. G., ed) Appleton-Lange, 1998, p 625.

    Greenspan, F.S., and Dong, B. J.. Histamine, Thyroid and Antithyroid Drugs, in Basic and Clinical Pharmacology, (Katzung, B. G., ed) Appleton-Lange, 1998, pp 619-633.

    Wartofsky, L., Diseases of the Thyroid, In Harrison's Principles of Internal Medicine 14th edition, (Isselbacher, K.J., Braunwald, E., Wilson, J.D., Martin, J.B., Fauci, A.S. and Kasper, D.L., eds) McGraw-Hill, Inc (Health Professions Division), 1998, pp 2012-2034

     

     

    Antithyroid Drugs:

     

    Hypothyroidism

     

     Hypothyroidism: Causes/Classification

    Thyroid
    Thyroprivic* Goitrous
    Congenital development defect
    • Biosynthesis defect (genetic)
    • Idiopathic (primary)
    • Transmitted by the mother (antithyroid drugs)
    • Postablative {postsurgical,131I}
    • Iodine deficiency
    • Postradiation {e.g. for lymphoma}
    • Drug-induced {e.g. salicylates, lithium,iodides, phenylbutazone,iodoantipyrine}
     
    • chronic thyroiditis (Hashimoto's disease); interleukin 2

    Suprathyroid (Trophoprivic)
    Pituitary Hypothalamic
    Panhypopituitarism Congenital defect
    Isolated low TSH levels Infection (e.g. encephalitis)
      Neoplasm; Infiltrative (sarcoidosis)

     

     

     

    *- Thyroprivic: refering to lack of thyroidhormone (e.g. removal of the gland or suppression of glandular function)

    Thyrotoxicosis:

    Graves' disease

    "Diffuse toxic goiter of Graves disease, gross, showing symmetric, non-nodular hypervascular enlargement of the thyroid"

    1999 KUMC Pathology and the University of Kansas, used with permission; courtesy of Dr. James Fishback, Department of Pathology, University of Kansas Medical Center.

     

    Greenspan, F.S., and Dong, B. J.. Histamine, Thyroid and Antithyroid Drugs, in Basic and Clinical Pharmacology, (Katzung, B. G., ed) Appleton-Lange, 1998, pp 619-633.

    Wartofsky, L., Diseases of the Thyroid, In Harrison's Principles of Internal Medicine 14th edition, (Isselbacher, K.J., Braunwald, E., Wilson, J.D., Martin, J.B., Fauci, A.S. and Kasper, D.L., eds) McGraw-Hill, Inc (Health Professions Division), 1998, pp 2012-2034

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