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THYROID& ANTITHYROID
Thyroid Gland


One of the largest endocrine glands
Secretes three hormones essential for proper
regulation of metabolism
– Thyroxine (T4)
– Triiodothyronine (T3)
– Calcitonin


Located near the parathyroid gland
Involved in many bodily processes, growth, body
temperature regulation, cardiovascular, endocrine
& neuromuscular functions.

Iode from diet is responsible for the
synthesis thyroglobuline

Hypothalamus secretes TSH that stimulates
the thyroid to break down thyroglobulin into
T3(iodine 59%) & T4(iodine 65%) and is
released into the circulation
Tahapan sintesa & sekresi :
1.
2.
3.
4.
5.
uptake yodida
oksidasi & yodinasi
pembentukan T4 & T3 dari yodotirosin
sekresi hormon tiroid
konversi T4 T3 di jar. perifer

enz.5-deyodinase

dihambat oleh : malnutrisi, hipoglikemi,
kortikosteroid,  bloker,
PTU, defisiensi Se dll.
Kel.tiroid
I-  I-
peroxidase I*
tyroglobulin
MIT, DIT, T3, T4
transport
I- tyr
MIT, DIT
proteolisis
exocytosis
T4, T3 (ikt.protein)
darah
Jar. perifer : T4, T3
T3
Mekanisme Kerja :
Melalui reseptor tiroid di dlm sel  regulasi gen
spesifik

pertumbuhan & metabolisme
1. Tiroid diperlukan unt.tumbuh kembang
termsk CNS  hipotiroid (hamil)kretinisme
2. Efek kalorigenik : T4 meningkatkan
metabolisme, katabolisme, pembentukan
kalori , termogenesis, vasodilatasi perifer,
curah jantug .
3. CVS
takhikardia, CO , SV , hipertropi
Hypothyroidism:
Deficiency in Thyroid Hormones

Primary: abnormality in the thyroid gland
itself. Most common cause is hashimoto’s
thyroiditis.

Secondary: results when the pituitary gland
is dysfunctional and does not secrete TSH
Thyroid abnormalities
Cretinism: Hyposecretion of thyroid hormone during
youth. Low metabolic rate, retarded growth and sexual
development, possibly mental retardation
Myxedema: Hyposecretion of thyroid hormone as an adult.
Decreased metabolic rate, loss of mental and physical
stamina, weight gain, loss of hair, firm edema, yellow
dullness of the skin

Goiter: Enlargement of the thyroid gland. Results from
overstimulation by elevated levels of TSH. TSH is elevated
because there is little or no thyroid hormone in circulation
Hypothyroidism

Common symptoms
–
–
–
–
–
Thickened skin
Hair loss
Constipation
Lethargy
Anorexia
Thyroid Preparations

levothyroxine * most common
– Synthetic thyroid hormone T4

liothyronine
– Synthetic thyroid hormone T3
Mechanism of Action
Thyroid preparations are given to replace
what the thyroid gland cannot produce to
achieve normal thyroid levels.
 Thyroid drugs work the same way as
thyroid hormones

Indications
To treat all three forms of hypothyroidism
 levothyroxine is the preferred agent because its
hormonal content is standardized; therefore, its
effect is predictable
Also used for thyroid replacement in clients whose
thyroid glands have been surgically removed or
destroyed by radioactive iodine in the treatment of
thyroid cancer or hyperthyroidism

Side Effects
Cardiac dysrhythmia is the most significant
adverse effect
 May also cause:

– Tachycardia, palpitations, angina, hypertension,
insomnia, tremors, headache, anxiety, nausea,
diarrhea, menstrual irregularities, weight loss,
sweating, heat intolerance, others
Hyperthyroidism
Excessive Thyroid Hormones:
free T3 & T4
 Caused by several diseases
–
–
–
–
–
–
Graves’ disease
Toxic nodular disease
Multinodular disease
Thyroid storm
Thyroid cancer
Pituitary hormones
Hyperthyroidism

Affects multiple body systems, resulting in an
overall increase in metabolism
–
–
–
–
–
–
–
Wt loss
Diarrhea
Flushing
Increased appetite
Muscle weakness
Sleep disorders
Altered menstrual flow
– Fatigue
– Palpitations
– Nervousness
– Heat intolerance
– Irritability
Treatment of Hyperthyroidism
Surgery to remove all or part of the thyroid gland
Antithyroid drugs
1. Prevent hormone thyroid synthesis
2. Prevent yodide ion transport/anion inhibitors
3. Yodides  prevent synthesis & release thyroid
hormone
4. Radioactive iodine
5.  bloker
Kel.tiroid
I-  I-
tyroglobulin
MIT, DIT, T3, T4
peroxidase I*
transport
I- tyr
PTU
MIT, DIT
SCN
ClO4
proteolisis
exocytosis
Yod
T4, T3 (ikt.protein)
darah
Jar. perifer : T4, T3
bloker
T3
1. Prevent hormone thyroid synthesis
contoh obat : PTU (propilthiourasil), Metimazol,
Karbimazol, Metiltiourasil
Farmakokinetik :
per oral, distribusi slrh tubuh,
ekskresi mel. urin & ASI
masa kerja pendek  8 jam (PTU)
Efek samping :
demam, purpura, agranulositosis, ikterus,
goiter pada fetus (dose dependent)
Sering digunakan bersama yodium untuk mengurangi
vaskularisasi pra operasi
2. Prevent iodide ion transport
Drug exp : thiocyanate (SCN-), perchlorate(ClO4-).
Effect : block uptake iodideprevent thyroid functions
3. Yodide
Drug exp : natrium yodida, kalium yodida
(lugol solution)
Effect : inhibit release & organification thyroid horm
decrease the size and vascularity of gland
4. Radioactive iodine
Drug exp. : I131
Effect : I131 works by destroying the thyroid gland
5.  BLOKER
Prevent yodisation T4, clinical improvement
Tugas :
Buat ringkasan tentang hormon
Paratiroid dan regulasi calcium
Sifat kimia
Sintesa dan sekresi
Fungsi fisiologis
Regulasi sekresi
Efek pada organ : tulang dan ginjal