1. 8-Jul-16Thyroid Hormones1 Normal Functions HyperthyroidismHypothyroidism

2. 8-Jul-16Thyroid Hormones2  Two principal hormones Thyroxin (T 4 ) Thyroxin (T 4 ) Triiodothyronin (T 3 ) Triiodothyronin (T 3 )  Others Calcitonin Calcitonin Parathyroid hormones Parathyroid hormones

3. 8-Jul-16Thyroid Hormones3 Thyroid Hormones Effects  Cellular metabolic activity  Thyroid hormone  Metabolic activity of almost all tissues  Metabolic activity of almost all tissues BMR can  to 60 – 100% above normal BMR can  to 60 – 100% above normal Rate for utilization of food for energy is increased Rate for utilization of food for energy is increased Rate of protein synthesis  but also the rate of prot catabolism  Rate of protein synthesis  but also the rate of prot catabolism 

4. 8-Jul-16Thyroid Hormones4 Thyroid Hormones Effects  Growth rate of young people accelerated  Mental processes excited  Activity of most other endocrine glands are increased  Increase in mitochondria  Increase membrane active transport mechanism

5. 8-Jul-16Thyroid Hormones5 Effect on Growth  In children Hypothyroid causes Hypothyroid causes  Retarded growth In those who are hyperthyroid In those who are hyperthyroid  Excessive skeletal growth  Giant  Thyroid hormone promote growth and development of brain During fetal life During fetal life

6. 8-Jul-16Thyroid Hormones6 Effect on Carbohydrate  Stimulate all aspect of carbohydrate metabolism Uptake of glucose by cells Uptake of glucose by cells Enhanced glycolysis Enhanced glycolysis Enhanced gluconeogenesis Enhanced gluconeogenesis  Absorption by GIT  Absorption by GIT  insulin secretion  insulin secretion

7. 8-Jul-16Thyroid Hormones7 Effect on Fat  Thyroid hormones  Enhance all aspects of fat metabolism Rapid mobilization of lipids from adipose tissues Rapid mobilization of lipids from adipose tissues   In fat stores  in FFA conc in plasma  in FFA conc in plasma Increased FA oxidation by cells Increased FA oxidation by cells

8. 8-Jul-16Thyroid Hormones8 Effect on Fat  Effect on plasma & liver fat   Thyroid hormones  conc of cholesterol, phospholipids, TG in plasma  conc of cholesterol, phospholipids, TG in plasma But increase FFA But increase FFA   Thyroid hormones Increase conc of cholesterol, phospholipids, TG Increase conc of cholesterol, phospholipids, TG Cause excessive deposition of fat in liver Cause excessive deposition of fat in liver

9. 8-Jul-16Thyroid Hormones9 Effect on Fat   Cholesterol can lead to artherosclerosis  Thyroid hormone Increase cholesterol secretion in bile Increase cholesterol secretion in bile

10. 8-Jul-16Thyroid Hormones10 Specific effects  On CVS Decrease TPR Decrease TPR  Heat & waste products Increase 2:3 DPG Increase 2:3 DPG  Relative tissue hypoxia Increase sensitivity and number Increase sensitivity and number  Β-adrenergic receptors  ↑ CO Increase blood flow to all tissues except brain Increase blood flow to all tissues except brain

11. 8-Jul-16Thyroid Hormones11 Specific Effects  Increase O 2 consumption in most tissue except Testes, brain, erythrocytes, spleen Testes, brain, erythrocytes, spleen  GIT Increase absorption of Increase absorption of  Vitamins A, B 12, Iron  CNS Promote normal Brain development Brain development Myelination Myelination Excitability of tissues & reflexes Excitability of tissues & reflexes  Potentiation of catecholamines

12. 8-Jul-16Thyroid Hormones12 Abnormal Thyroid Functions HyperthyroidismHypothyroidism

13. 8-Jul-16Thyroid Hormones13 Hyperthyroidism  Primary  Secondary

14. 8-Jul-16Thyroid Hormones14 Primary Hyperthyroidism Associated with Associated with  Low TSH  Hyperplasia of the gland An auto immune response An auto immune response More than 50% of patients More than 50% of patients  Show eye signs  Grave’s disease

15. 8-Jul-16Thyroid Hormones15 Primary Hyperthyroidism  Grave’s diseases Exophthalmic goiter Exophthalmic goiter Thyroid gland becomes Thyroid gland becomes  Enlarged  Hyperplastic  Long acting thyroid stimulator (LATS)  Long acting thyroid stimulator protector (LATS-protector) TSH levels normal TSH levels normal

16. 8-Jul-16Thyroid Hormones16 Secondary Hyperthyroidism  Hypothalamic or pituitary in origin  Associated with high plasma THRH  Plasma TSH levels are raised

17. 8-Jul-16Thyroid Hormones17 Clinical Manifestation  These are exaggerated effects of Normal thyroid functions on Normal thyroid functions on  CVS, GIT, CNS  Metabolism  These include Heat intolerance Heat intolerance Raised CO Raised CO  HR  HR Emotional irritability Emotional irritability Fine tremors Fine tremors

18. 8-Jul-16Thyroid Hormones18 Complications of Hyperthyroidism  Exopthalmos  High output cardiac failure  Inadequate tissue perfusion Despite the compensatory  Co Despite the compensatory  Co  Liver failure  demand energy, vitamins  demand energy, vitamins  Depletion of vit A, B 12  Anaemia Depletion of glycogen Depletion of glycogen  Liver becomes more susceptible to injury & failure

19. 8-Jul-16Thyroid Hormones19 Hypothyroidism  Decreased or suppressed TH activity  Could Primary hypothyroidism Primary hypothyroidism Secondary hypothyroidism Secondary hypothyroidism

20. 8-Jul-16Thyroid Hormones20 Primary hypothyroidism  Decreased or suppressed activity of TH Due to diseases of the thyroid gland Due to diseases of the thyroid gland  Associated with autoimmune response Hashimoto’s disease Hashimoto’s disease  Some are due to idiopathic non-toxic goiter

21. 8-Jul-16Thyroid Hormones21 Secondary Hypothyroidism  May be due to Failure of pituitary or hypothalamus Failure of pituitary or hypothalamus Iodine deficiency Iodine deficiency Presence of goitrogenic substances Presence of goitrogenic substances  Carbamazole  Cabbages

22. 8-Jul-16Thyroid Hormones22 Secondary Hypothyroidism  Thyroid gland respond to a dose of TSH  To differentiate hypothyroidism Secondary for Pituitary or hypothalamic failure Secondary for Pituitary or hypothalamic failure  Exogenous TRH administration  in plasma TSH if the problem is due to hypothalamic failure  in plasma TSH if the problem is due to hypothalamic failure There is no  in plasma TSH if the failure is of pituitary gland There is no  in plasma TSH if the failure is of pituitary gland

23. 8-Jul-16Thyroid Hormones23 Manifestations of Hypothyroidism  In adults Called myxodema Called myxodema Characteristic skin changes Characteristic skin changes  Skin dry, yellowish (carotenemia)  Carotene retention in the skin BMR falls to about 40% of normal BMR falls to about 40% of normal Poor tolerance to cold Poor tolerance to cold Voice husky and slow Voice husky and slow Mental activity Mental activity  Slow, poor memory  Severe mental illness (myxodema madness)

24. 8-Jul-16Thyroid Hormones24 Manifestations of Hypothyroidism  In children and young Cretinism Cretinism  Dwarfed, retarded growth Mentally retarded dwarfs Mentally retarded dwarfs  Reduced nerve cells and axons in CNS  Reduction in myelination Enlarged protruded tongue Enlarged protruded tongue  Speech problems Pot bellied due to Pot bellied due to  Accumulation of fluids in abdominal cavity