HYPERTHYROIDISM-lecture.ppt
- 2. background • Clinical syndrome resulting from exposure of tissues to excess circulating levels of free thyroid hormones • It is five times more commoner in females
- 3. • Highly vascular gland located anteriorly in the lower neck • Synthesises and stores two important but different types of hormones: ➢Iodothyronine hormone –Thyroxine (T4) ➢Triiodothyronine(T3) –released from T4 in the peripheral tissues ; most active hormone ➢essential for normal growth and development
- 4. • The function of the thyroid gland is regulated by a feedback mechanism involving hypothalamic-pituitary axis in the brain. • TSH from the anterior pituitary gland which is regulated by the TRH from the hypothalamus. TSH stimulate T4 and T3 production from the glands
- 5. THYROID HORMONES • THYROXINE • T4: (Thyroxine) is made exclusively in thyroid gland • Secretion of T4 to T3 : 10:1 • Potency of T4 to T3; 1:10 • T4 is the most important source of T3 by peripheral tissue deiodination“ T4 to T3 “
- 6. Etiology • Gravis disease-76% • Multinodular goitre • Autonomously functioning solitary thyroid nodule • Thyroiditis Subacute Pospartum • Drugs - amiodarone
- 7. Grave’s disease • Autoimmune process in which serum IgG antibodies bind to TSH receptors and stimulate thyroid hormone production, behaving like TSH • These antibodies are called thyroid stimulating antibodies • Most pts are aged between 30-50
- 8. Clinical features • Goitre- diffuse + bruit, nodular • GIT Wt loss despite normal or increased appetite Hyperdefaction (frequent bowel motions) Diarrhea Anorexia, vomiting
- 9. Clinical features • Cardiorespiratory Palpitations, sinus tachycardia Increased pulse pressure Ankle oedema in absence of cardiac failure Angina, cardiomyopathy, ccf Dyspnoea, exacerbation of asthma
- 10. Clinical features • Neuromuscular Nervousness, irritability, psychosis • Dermatology Increased sweating, pruritus, palmar erythema, Alopecia, vitiligo, myxoedema
- 11. Clinical features • Reproductive Amenorrhea/ oligomenorrhea Infertility, spontaneous abortion Loss of libido, impotence • Ocular Excessive lacrimation, exophalmos, diplopia, papilloedema, loss of visual acuity
- 12. Clinical features • Other Heat intolerance Fatigue, apathy Lyphadenopathy Thirst osteoporosis
- 13. Management • Three methods Antithyroid drugs Subtotal thyroidectomy Radioactive iodine
- 14. Treatment • ANTITHYRIOD DRUGS : • CARBIMAZOLE • METHIMAZOLE • PROPYLTHIOURACIL
- 15. CARBIMAZOLE These drugs inhibit thyroid hormone production. Full dose of carbimazole (40mg/day) are give to suppress the thyroid gland completely while replacing thyroid activity with100 mcg of thyroxin daily once euthyroid state is achieved. This continues for 18 months
- 16. METHIMAZOLE • Same mechanism of action as carbimazole Dose; 30mg/day until someone is euthyroid ( 4- 6 weeks) Maintenance dose; 5-10mg
- 17. PROPYLTHIOURACIL • Inhibits production of thyroxine hormone and stops the conversion of T4 to T3 in the peripherals. • 300 -450mg /day • Maintenance dose of 50-100mg/day
- 18. Adverse effects • Rash • Fever • Anorexia & nausea • Agranulocytosis • Aplastic Anaemia • Liver damage
- 19. Radioiodine • Emits beta radiation that destroys the gland. • Cant be used in pregnant women.
- 20. Surgery • Surgical remove of the gland in individuals that cant use radioiodine.
- 21. Beta blockers • Propranolol : used for symptomatic relief • Blocks beta receptors that are activated by increased amount of the hormone • Blocks the conversion of T4 to T3.
- 22. HYPOTHYROIDISM
- 23. introduction • It may be primary from the disease of the thyroid gland or secondary to hypothalamic –pituitary disease
- 24. CLINICAL FEATURES • General; Tiredness, wt gain, cold intolerance Hoarseness Goitre Bradycardia Constipation Impotence Skin problems
- 25. Thyroid Preparations These preparations may be synthetic (levothyroxine, liothyronine, liotrix) or of animal origin (desiccated thyroid). Synthetic levothyroxine is the preparation of choice for thyroid replacement and suppression therapy because of its 1- stability 2- content uniformity 3- low cost 4- lack of allergenic foreign protein 5- easy laboratory measurement of serum levels 6- long half-life (7 days), which permits once-daily administration. • In addition, T4 is converted to T3 intracellularly; thus, administration of T4 produces both hormones.
- 26. Although liothyronine (T3) is three to four times more potent than levothyroxine, it is not recommended for routine replacement therapy because of its 1- shorter half-life (24 hours), which requires multiple daily doses 2- its higher cost 3- the greater difficulty of monitoring 4- its greater hormone activity and consequent greater risk of cardiotoxicity, T3 should be avoided in patients with cardiac disease. It is best used for short-term suppression of TSH.
- 27. Treatment • Levothyroxine(T4) • Dose: 50 -100microgram/day • Liothyronine (T3) • 5-20microgram/day
- 28. Adverse effects • Increase in the metabolic rate • Myocardial ischaemia • Atrial fib