34. Deiodinasas Bogazzi F, The various effects of amiodarone on thyroid function. Thyroid;11:511-19, 2001 Hipo Hiper Hipo Disminuye Hiper Hipo Hiper Aumenta INT EXT EXT Diodinación anillo Placenta, SNC, piel, H SNC,P,gra- sa, placenta H,R,M,T Localización Inactiva T4 y T3 Provee T3 a la célula Provee T3 al plasma > abundancia Rol Tipo 3 Tipo 2 Tipo 1 Parámetro
35.
36.
37. TRH TSH T 3 , T 4 inhibición inhibición La falta de yodo disminuye la secreción de hormonas tiroideas
38. TRH TSH T 3 , T 4 desinhibición La disminución de hormonas tiroideas induce un aumento compensador de TRH y TSH desinhibición
39. TRH TSH T 3 , T 4 desinhibición El aumento de TRH y TSH devuelve la secreción de hormonas tiroideas a la normalidad desinhibición
40. TRH TSH desinhibición El aumento de TSH provoca un crecimiento del tiroides T 3 , T 4 BOCIO
48. MECHANISMS OF AMIODARONE ACTION ON THE THYROID Faizel Osman, et al. Circulation 2002;105:1275-1277 Effect Decreased transcription of TH- responsive genes Tissue hypothyroid-like condition Interaction with TH receptors Leakage of preformed TH Thyroid cytotoxicity Decreased peripheral T3 production Inhibition of TH entry into cells Increased TSH Inhibition of type II 5’-deiodinase Increased T4 Decreased T3 Inhibition of type I 5’-deiodinase Mechanism of action
49.
50. Prevalence (%) 10% 5% 2% 22% Tuscany, Italy Worcester, USA Prevalence of amiodarone-induced hyperthyroidism and hypothyroidism in an iodine-deficient area of Norther Tuscany, Italy, and in an iodine-sufficient area of Worcester, Massachusetts. ( Ann Intern Med 101:28-34, 1984 )
51.
52.
53. MANAGEMENT OF AMIODARONE-INDUCED HYPOTHYROIDISM Treatment Underlying thyroid abnormalities LT4 replacement No underlying thyroid abnormality Amiodarone cannot be withdrawn LT4 replacement Amiodarone can be withdrawn Follow-up