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18 Cards in this Set

  • Front
  • Back
Thyroid hormone effects
- nearly every organ system
- disorders have profound effects on entire body function
Thyroid biosynthesis
- iodinde from blood inot thyroid follicle
- peroxidase incorporates iodide into tyrosie residues
- T3 and T4 stored in follicle cells
- protease enzyme releases T4 and T3 from thyroglobulin protein into circulation
- T4 converted to active T3 by deiodination in the liver and kidney
- autoimmune (hashimoto's)
- gioterogens
- iodine deficiency
- drug induced
- radiation/thyroidectomy
- congenital
- dyshormonogenesis
- secondary (TSH deficit)
- Graves disease
- toxic nodular goiter
- subacute thyroiditis
= this will increase basal metabolic rate and increase beta-adrenergic activity
Drugs used in Hypothyroidism
- L-thyroxine (t4)
- Triiodothronine (T3)
- Liothyronine
- Levothyroxine??
Drugs used in Hyperthyroidism
- 131 I
- Thioamides, PTU, Methimazole
- K iodine
- Propranolol
Rationale to Tx of hypothyroidism
- long term needed
- T4 usually most appropriate
- dose changes made slowly
- physiologic doses cna mimic hyperthyroidism
- most suitable prep for tx of hypo
- long half life
- low cost
- converted to T3 and easy to monitor in the serum
- no immediate CV effects
Liothronine (triiodothyronine)
- active hormone
- more potent
- immediate CV effects
- may use this acutely and then switch to Levo
Rationale of Hyperthyroidism drugs
- destroy hyperactive cells or directly inhibit thryoid hormone syntheisis/release
- thioamide drugs, 131 I, K iodide
Thioamide Drugs
- Methimazole
- Propylthiouracil (PTU)
Mechanism of Thioamide drugs
- directly inhibit peroxidase enzyme in T4/T3 biosynthesis
- PTU also inhibits deiodination of T4 to T3 in the liver. Thus, blood levels of T3 decline more rapidly than T4
Effects and Toxicity of Thioamide drugs
- slow onset, takes 2-4 weeks to become euthyroid
- well tolerated, may see skin rash
Radioactive Iodine
- Tx of hyper
- active uptake exclusively into follicle cells - this allows localized tissue destruction
- caution with elderly and children, pregnant
- Complications= transient hyperthyroidism, permananent HYPO thyroidism
Potassium Iodide (KI)
- tx of hyper
- paradoxical inhibition of iodine uptake, peroxidase enzyme, and proteolytic release of T4-3
- KI is only drug that inhibits release!!!
- only has short term effect
- tx of hyper
- symptomatic control of excessive B-adrenergic action
- also inhibits T4 to T3 conversion in liver
- ALSO controls symptoms of hyperthyroidism
Iodinated Radiocontrast Media (Ipodate)
- tx of hyper
- inhibits T4 deiodination rapidly decreasing T3 concentrations
New Directions
- Combinations of agents used for long term effect
- using immunosupressive agents
-Exophthalmus- not sure what this is about