THYROID ANTITHYROID Thyroid Gland n n One of

THYROID& ANTITHYROID

Thyroid Gland n n One of the largest endocrine glands Secretes three hormones essential for proper regulation of metabolism – Thyroxine (T 4) – Triiodothyronine (T 3) – Calcitonin n n Located near the parathyroid gland Involved in many bodily processes, growth, body temperature regulation, cardiovascular, endocrine & neuromuscular functions.

n Iode from diet is responsible for the synthesis thyroglobuline n Hypothalamus secretes TSH that stimulates the thyroid to break down thyroglobulin into T 3(iodine 59%) & T 4(iodine 65%) and is T 3( T 4( released into the circulation

Tahapan sintesa & sekresi : 1. 2. 3. 4. 5. uptake yodida oksidasi & yodinasi pembentukan T 4 & T 3 dari yodotirosin sekresi hormon tiroid konversi T 4 T 3 di jar. perifer enz. 5 -deyodinase dihambat oleh : malnutrisi, hipoglikemi, kortikosteroid, bloker, PTU, defisiensi Se dll.

Kel. tiroid I- peroxidase I* tyroglobulin MIT, DIT, T 3, T 4 transport I- tyr MIT, DIT proteolisis exocytosis T 4, T 3 (ikt. protein) darah Jar. perifer : T 4, T 3

Mekanisme Kerja : Melalui reseptor tiroid di dlm sel regulasi gen spesifik pertumbuhan & metabolisme 1. 2. 3. Tiroid diperlukan unt. tumbuh kembang termsk CNS hipotiroid (hamil) kretinisme Efek kalorigenik : T 4 meningkatkan metabolisme, katabolisme, pembentukan kalori , termogenesis, vasodilatasi perifer, curah jantug . CVS takhikardia, CO , SV , hipertropi

Hypothyroidism: Deficiency in Thyroid Hormones n Primary: abnormality in the thyroid gland itself. Most common cause is hashimoto’s thyroiditis. n 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 n Goiter: Enlargement of the thyroid gland. Results from overstimulation by elevated levels of TSH is elevated because there is little or no thyroid hormone in circulation

Hypothyroidism n Common symptoms – Thickened skin – Hair loss – Constipation – Lethargy – Anorexia

Thyroid Preparations n levothyroxine * most common – Synthetic thyroid hormone T 4 n liothyronine – Synthetic thyroid hormone T 3

Mechanism of Action Thyroid preparations are given to replace what the thyroid gland cannot produce to achieve normal thyroid levels. n Thyroid drugs work the same way as thyroid hormones n

Indications To treat all three forms of hypothyroidism n 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 n

Side Effects Cardiac dysrhythmia is the most significant adverse effect n May also cause: n – Tachycardia, palpitations, angina, hypertension, insomnia, tremors, headache, anxiety, nausea, diarrhea, menstrual irregularities, weight loss, sweating, heat intolerance, others

Hyperthyroidism Excessive Thyroid Hormones: free T 3 & T 4 n Caused by several diseases – Graves’ disease – Toxic nodular disease – Multinodular disease – Thyroid storm – Thyroid cancer – Pituitary hormones

Hyperthyroidism n Affects multiple body systems, resulting in an overall increase in metabolism – – – – Wt loss Diarrhea – Fatigue Flushing – Palpitations Increased appetite – Nervousness Muscle weakness – Heat intolerance Sleep disorders – Irritability Altered menstrual flow

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- peroxidase tyroglobulin MIT, DIT, T 3, T 4 I* transport I- tyr PTU MIT, DIT SCN Cl. O 4 proteolisis exocytosis Yod T 4, T 3 (ikt. protein) darah Jar. perifer : T 4, T 3 bloker T 3

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(Cl. O 4 -). 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. : I 131 Effect : I 131 works by destroying the thyroid gland 5. BLOKER Prevent yodisation T 4, 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