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Thyroid Hormone Mech
- • TRH (Hypothalamus)
- →→ TSH (Pituitary)
- →→→ Thyroid Gland
- →→→ →T3/T4
• Thyroid hormone is required for growth and differentiation in utero
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Thyroid Hormone Deficiency
- • Cretinism
- • Poor differentiation
- • Eyes don’t know where to go
- • Mother & baby both hypothyroid
- • Mother’s T3/T4 last for at least 1 month of the babies life
- • Deficiency can not be noticed until the 2nd month of life
- • If it is deficient, Brain is at danger because it is still growing
- • Retardation
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Thyroid Composition
• T3/T4 are made from tyrosine and the have a nuclear membrane receptor
- • T3/T4 is responsible for the BMR
- • Basal Metabolic Rate
- • Therefore, it ALLOWS various functions to speed up
- • Permissive action
- • Lets other processes to their job
- • IF there is a deficiency everything will “shut down”
- • The Thyroid Gland always concentrates Iodine
- • Therefore, needs a ATPase b/c it is going against a gradient
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Thyroid Synthesis
- • Tyrosine → MIT/DIT + colloid
- • monoiodotyrosine (MIT)
- • diiodotyrosine (DIT)
- • = Thyroglobulin →
- • Peroxidase = 20%T3/80%T4
- • T3 is the biologically active form
- • T4 is changed to T3 by deiodinase from the liver
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Thyroid hormone storage
• rT3
• Often elevated when sick
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Thyroid Diagnose
- • SIGNAL
- • 1°: Organ
- • 2°: Pituitary
- • 3°: Hypothalamus
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Thyroid Hormone Disorders:
Hyperthyroidism
- • Grave’s Disease
- • autoimmune
- • < 50 y/o TSH antibody
- • Plummer’s Syndrome:
- • toxic multinodular goiter
- • > 50 y/o
- • one area hot (iodine takeup)
- • Tx: propanolol
- • Propylthiouracil-
- • blocks peroxidation
- • Methimazole-
- • block peroxidation
- • I-131
- • destroy the tissue
- • Thyroxine-
- • replacement
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Thyroid Hormone Disorders:
Hypothyroidism
• MCC: Iodine deficiency
- • Cretinism
- • Mom and fetus
- • hypo
- • Hashimoto’s disease
- • Autoimmune disease
- • DeQuarvain’s disease
- • Virus (painful)
- • self limiting
- • Lymphocytic thyroiditis
- • postpartum
- • Riedel’s Struma
- • capsule cancer
- • woody
- • Tx:
- • Thyroxine (T-4)
- • L-Thyronine (T-3)
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