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A ppt on THYROID HORMONESAND THYROID INHIBITORS By Dr.Nanita Agrawal, Dr. Prashant,MD 1dr prashant's.

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Presentation on theme: "A ppt on THYROID HORMONESAND THYROID INHIBITORS By Dr.Nanita Agrawal, Dr. Prashant,MD 1dr prashant's."— Presentation transcript:

1 A ppt on THYROID HORMONESAND THYROID INHIBITORS By Dr.Nanita Agrawal, Dr. Prashant,MD 1dr prashant's


3 I. THYROID HORMONE A.INTRODUCTION The thyroid hormone secretes 3 hormones: 1. Thyroxine (T4) 2. Tryiodothyronine (T3) 3. Calcitonin Former 2 are produced by thyroid follicles. Calcitonin produced by interfollicular c cells. 3dr prashant's

4 B. ACTIONS Growth and development: Essential for normal growth and development. Intermediary metabolism: Marked effect on lipid, carbohydrate and proteinmetabolism. Calorigenesis: Increase BMR. CVS: Heart rate, contractility and output are increased. GIT: Propulsive activity increased. 4dr prashant's

5 Nervous system: Mental retardation is the hallmarkof cretinism. Skeletal muscle: Muscles flabby and weak in myxoedema. Kidney: Rate of urine flow is often increased. Haemopoiesis: Facilitatory to erythropoiesis. Reproduction: Indirect effect on reproduction. 5dr prashant's

6 C. MECHANISM OF ACTIONS T3 (and T4) penetrate cells. Combine with a nuclear receptor. A specific DNA sequece called thyroid hormone response element has been identified. T3-receptor complex binds. Derepression of gene transcription 6dr prashant's

7 D. PREPRATIONS 1 -thyroxin sod: Electroxin Roxin 100 ug tab. Thyranorm Thyrox 25 ug, 50 ug, 1 00 ug tabs. 7dr prashant's

8 E. USES Cretinism: Due to failure of thyroid development. Detected during infancy or childhood. Mental retardation. Adult hypothyroidism: Develops as a consequence of thyroiditis, thyroidectomy, treatment with goiterogens; may accompany simple goiter if iodine. Myxoedema coma: Thyroid nodule: 8dr prashant's

9 Nontoxic goiter: May be endemic or sporadic.deficient production of thyroid hormone leads to excess TSH-throid enlarges. Papillary carcinoma of thyroid: Empirical uses: Refractory anaemias Menstrual disorders, infertility not corrected by usual treatment. Chronic/ non healing ulcers Obstinate constipation 9dr prashant's

10 2. THYROID INHIBITORS INTRODUCTION Drugs used to lower the functional capacity of the hyperactive thyroid gland. Throtoxicosis Two main causes are Graves disease and toxic nodular goiter 10dr prashant's

11 B. CLASSIFICATION Inhibit hormone synthesis (Antithyroid drugs) propylthiouracil, methimazole, carbimazole. Inhibit iodide trapping (ionic inhibitors) thiocynates (-SCN), perchlorates (-C 1 O4), nitrates (-NO3). Inhibit hormone release iodine, iodides of Na and K, organic iodide. Destroy thyroid tissue Radioactive iodine. 11dr prashant's

12 3. ANTITHYROID DRUGS A.INTRODUCTION Inhibit iodination of tyrosine residues in thyroglobulin. Inhibit coupling of iodotyrosine residues to form T3 and T4. 12dr prashant's

13 B. PHARMACOKINETICS Quickly absorbed orally Cross placenta Metabolised in liver Excreted in urine 13dr prashant's

14 C. ADVERSE EFFECTS Hypothyroidism due to over treatment common but reversible. G.I. Intolerance, skin rashes and joint pain. Loss or graying of hair, loss of taste, fever and liver damage. Agranulocytosis 14dr prashant's

15 D. PREPARATIONS AND DOSE Propyltjiouracil : mg TDS followed by mg BD-TDS for maintenance PTU 50 mg tab. Methimazole: 5-10 mg TDS initially, maintenance dose 5-15 mg daily in 1-2 divided doses. Carbimazole: 5-15 mg TDS initially, maintenance dose mg daily in 1-2 divided doses, neo mercazole, thyrozole, antithyrox 5 mg tab. Carbimazole is more commonly used in india. 15dr prashant's

16 E. USES The following strategies are adopted: 1)Definitive therapy: Preferred in young patient with a short history. 2)Preoperatively: Carbimazole before performing partial thyroidectomy. 3)Along with 131 I. 16dr prashant's

17 F. ADVANTAGES OVER SURGERY No surgical risk Hypothyroidism, if induced, is reversible. Can be used even in children and young adults. 17dr prashant's

18 G. DISADVANTAGES Prolonged treatment is needed. Not practicable in uncooperative/ unintelligent patient. Drug toxicity. 18dr prashant's

19 4. IODINE AND IODIDES A.INTRODUCTION Inhibition of hormone release- thyroid constipation. B. PRERARATION AND DOSE Lugols solution Colloid iodine 10% Collosol 19dr prashant's

20 C. USES Preoperative preparation Thyroid storm Prophylaxis of endemic goiter Expectorant Antiseptic 20dr prashant's

21 D. ADVERSE EFFECTS Acute reactions: Swelling of lips. Eyelids, angioedema of larynx (may be dangerous), fever, joint pain. Chronic overdose (iodism): Long term use of high doses can cause hypothyroidism and goiter. 21dr prashant's

22 5.RADIOACTIVE IODINE A.INTRODUCTION 131I: Physical half life 8 days- most commonly used. 123I: Physical half life 13 hours- only rarely used diagnostically. 125I: Physical half life 60 days. 131I emits x-rays as well as B particles. 22dr prashant's

23 B particles utilized for their destructive effect on thyroid cells. 131I is concentrated by thyroid. Incorporated in colloid- emits radiation from within the follicles Thyroid follicular cellsundergo pyknosisand necrosis followed by fibrosis. 23dr prashant's

24 Diagnostic u curie is given. Therapeutic Average therapeutic dose is 3-6 m curie. 24dr prashant's

25 B. ADVANTAGES Treatment is simple, conveniently inexpensive. No surgical risk, scar or injury to parathyroids/ recurrent laryngeal nerves. Cure is permanent. 25dr prashant's

26 C. DISADVANTAGES Hypothyroidism Long latent period of response. Contraindicated during pregnancy- cretinism. Not suitable for Young patients. 26dr prashant's

27 6. B ADRENERGIC BLOCKERS Propranolol During thyrotoxic crisis. While awaiting response to carbimazole or 131I. Along with iodide for preoperative preparation before subtotal thyroidectomy. 27dr prashant's

28 Our other websites dr prashant's 28

29 We thank our students who attend our classes in large numbers and motivate/encourage us to learn and teach better. You can also send any study material suitable for undergrads to us at

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