THYROID

DR. LAXMIKANTA SAY
INTRODUCTION


“Thyreos” - “A shield”



Largest endocrine gland



Development – floor of pharynx & thyroglossal duct
...
INTRODUCTION

CONT….



Functions of Thyroid



Maintains Metabolism in tissue
- stimulate O2 consumption
- regulate lip...
ANATOMY
BLOOD SUPPLY

HISTOLOGY
HORMONES
 T4
 T3
 RT3

 Calcitonin
IODINE HOMEOSTASIS
SYNTHESIS
Thyroid Cellular Mechanism
1.Iodine trapping
 2.Oxidation
 3.Synthesis of Thyroglobulin
 3.Organification – I...
CHEMISTRY
STORAGE


In Thyroglobulin molecule in colloid

MIT-23%
 DIT-33%
 T3-7%
 T4-35%
 RT3- Traces

SECRETION
THYROI
D
4µg/dl

27µg/dl

80µg/dl

T4

T3
31µg/dl

2µg/dl

36µg/dl
RT3

17μg/dl

38µg/dl
CARRIAGE



T3 & T4 exist in both free & protein bound form
Total plasma T4=8 µgm/dl , T3=0.15 µgm/dl

Plasma
protein
TB...
METABOLISM

T4
- 97% of T4 is secreted from thyroid
- 99.98 % plasma bound
- Plasma conc. 2 ng/dL
- Half-Life – 6-7 days
-...
METABOLISM

T3
- Normal Plasma level – 0.15 µg/dL
- TBG – 99.8%
- 0.2% free (0.3ng/dL)
- Half-Life – 1-2 days
- More poten...
METABOLISM


Release of T3 & T4



Deiodinase (D1/D2/D3)
- a.a selenocycsteine




Factors affecting deiodination
- fe...
TSH


Glycoprotein of 211 aminoacids.



MW. – 28,000.



Secretion is pulsatile – midnight secretion



Normal secret...
EXTRA THYROID TISSUE OF NIS
 Salivary

gland,
 Gastric mucosa,
 placenta,
 Cilliary body,
 Choroid plexus,
 Mammary ...
THYROID HORMONE ACTIVATION OF TARGET
CELLS
METABOLIC ACTION













Protein metabolism – Anabolic/ Catabolic
/Myopathy/Osteoporosis
Carbohydrate meta...
TRH SECRETION
(+) Cold
 (-) heat, stress,
T3,T4


TSH SECRETION
(+) T3, T4
 (-) glucocortiod,
dopamine, stress,
somatos...
REGULATION
1. TSH
i. Increased proteolysis of Thyroglobulin
ii. Increased activity of the Iodide pump
iii. Increased Iodin...
REGULATION
APPLIED ASPECTS
Goiter
 Hyperthyroidism
 Hypothyroidism

GOITER
GOITROGENS
Iodine deficiency
 Iodine excess
 Monovalent anions
 Coupling blocker
 Inhibitors of iodide conversion
 Ve...
HYPERTHYROIDISM
CAUSES
THYROID OVER ACTIVITY
1. Grave's disease (60 -80% )
2.Thyroid Multi Nodular Goiter
3.Solitary toxic...
SYMPTOMS














Heat intolerance,
fatigability,
exertional dyspnea,
symptom of vit
deficiency,
excitabili...
HYPOTHYROIDISM

CRETINISM

MYXEDEMA

HYPOTHYROIDISM
CRETINISM
CAUSES
- maternal I2 deficiency,
- fetal thyroid dysgenesis,
- Inborn errors of TH synthesis,
- maternal antithy...
CRETINISM
MYXEDEMA
CAUSES-Iodine deficiency
Autoimmune
Iatrogenic
Infiltrative disease
Pituitary failure
Hypothalamic
SYMPTOM
Tiredness, weakness,
dry skin, feeling cold,
hair loss, poor
memory,
constipation, wt gain,
poor appetite,
menorrh...
SCREENING OF THYROID DISORDER
THYROID FUNCTION TEST
Tests based on primary function of thyroid
1-radioiodine uptake study
2-PBI131 in serum
3.Butanol Ex...


Tests based on metabolic function of TH

1-BMR
2-Serum cholesterol level
3-Serum creatinine level
4-Blood sugar level

...
ANTITHYROID DRUGS
1. Drugs inhibit trapping of iodide (I-)
- Monovalent anions & metabolic poisons.
2. Thyourylenes
- Thyo...
THANK YOU
Thyroid
Thyroid
Thyroid
Thyroid
Thyroid
Thyroid
Thyroid
Thyroid
Upcoming SlideShare
Loading in …5
×

Thyroid

500
-1

Published on

Published in: Health & Medicine
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
500
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
21
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Thyroid

  1. 1. THYROID DR. LAXMIKANTA SAY
  2. 2. INTRODUCTION  “Thyreos” - “A shield”  Largest endocrine gland  Development – floor of pharynx & thyroglossal duct  Wt. 15 – 20 gms  Highly vascular – 5 ml/gm/min  Thyroglobulin - Mol. Wt. 3,35,000
  3. 3. INTRODUCTION CONT….  Functions of Thyroid  Maintains Metabolism in tissue - stimulate O2 consumption - regulate lipid & Carbohydrate metabolism - influence body mass & mentation  Secretion of Calcitonin - regulates Calcium levels
  4. 4. ANATOMY BLOOD SUPPLY HISTOLOGY
  5. 5. HORMONES  T4  T3  RT3  Calcitonin
  6. 6. IODINE HOMEOSTASIS
  7. 7. SYNTHESIS Thyroid Cellular Mechanism 1.Iodine trapping  2.Oxidation  3.Synthesis of Thyroglobulin  3.Organification – Iodination of Tyrosine  4.Release 
  8. 8. CHEMISTRY
  9. 9. STORAGE  In Thyroglobulin molecule in colloid MIT-23%  DIT-33%  T3-7%  T4-35%  RT3- Traces 
  10. 10. SECRETION THYROI D 4µg/dl 27µg/dl 80µg/dl T4 T3 31µg/dl 2µg/dl 36µg/dl RT3 17μg/dl 38µg/dl
  11. 11. CARRIAGE   T3 & T4 exist in both free & protein bound form Total plasma T4=8 µgm/dl , T3=0.15 µgm/dl Plasma protein TBG Conc. of T4 Half Life PP (mg/dl) 5 days 2 67% 46% TT 2 days Albumin 13 days T3 15 20% 1% 3500 13% 53%
  12. 12. METABOLISM T4 - 97% of T4 is secreted from thyroid - 99.98 % plasma bound - Plasma conc. 2 ng/dL - Half-Life – 6-7 days - Longer duration of action. - Volume of distribution – 15% of body wt.(10L) - Prohormone - metabolically inert until deiodinated - 1/3 rd metabolized to T3 & 45% to RT3. - Liver – Sulphation & Glucoronidation - Daily loss in stool – 4-5%
  13. 13. METABOLISM T3 - Normal Plasma level – 0.15 µg/dL - TBG – 99.8% - 0.2% free (0.3ng/dL) - Half-Life – 1-2 days - More potent & more active. - 13% of circulating T3 is by Thyroid - 87% deiodination of T4.
  14. 14. METABOLISM  Release of T3 & T4  Deiodinase (D1/D2/D3) - a.a selenocycsteine   Factors affecting deiodination - fetal life, - drugs, - selenium, - illness, - fasting,  Plasma t1/2 - T4-6-7days, T3 -1-2days
  15. 15. TSH  Glycoprotein of 211 aminoacids.  MW. – 28,000.  Secretion is pulsatile – midnight secretion  Normal secretion - 110 µgm/ day  Plasma level – 0.2–5.0 µ IUunit/ml  Half Life – 60 min.
  16. 16. EXTRA THYROID TISSUE OF NIS  Salivary gland,  Gastric mucosa,  placenta,  Cilliary body,  Choroid plexus,  Mammary gland
  17. 17. THYROID HORMONE ACTIVATION OF TARGET CELLS
  18. 18. METABOLIC ACTION            Protein metabolism – Anabolic/ Catabolic /Myopathy/Osteoporosis Carbohydrate metabolism – Increased Fat metabolism – Decreased Cholesterol BMR – Increased Vitamins – Increased requirement Body Weight – Decreased /Increased CVS – BF,CO,HR,SBP, decreased DBP, RR CNS – Nervousness, anexity, psychoneurotic tendencies Sleep – Tiredness, difficult to sleep Effect on Endocrine Glands – Secretion of Insulin, ACTH Sexual Functions – Impotence, Menorrhagia,
  19. 19. TRH SECRETION (+) Cold  (-) heat, stress, T3,T4  TSH SECRETION (+) T3, T4  (-) glucocortiod, dopamine, stress, somatostatin,  T3, T4  FACTORS OF REGULATION
  20. 20. REGULATION 1. TSH i. Increased proteolysis of Thyroglobulin ii. Increased activity of the Iodide pump iii. Increased Iodination of Tyrosine iv. Increased size & Increased secretory activity v. Increased no. Of thyroid cells & change of epithellium from cuboidal to columnar. 2. cAMP mediated stimulatory effect. 3. TRH mediated - Activation of phospholipase
  21. 21. REGULATION
  22. 22. APPLIED ASPECTS Goiter  Hyperthyroidism  Hypothyroidism 
  23. 23. GOITER
  24. 24. GOITROGENS Iodine deficiency  Iodine excess  Monovalent anions  Coupling blocker  Inhibitors of iodide conversion  Vegetables – Progoitrin, Progoitrin  Activator, Goitrin active antithyroid agent
  25. 25. HYPERTHYROIDISM CAUSES THYROID OVER ACTIVITY 1. Grave's disease (60 -80% ) 2.Thyroid Multi Nodular Goiter 3.Solitary toxic adenoma 4.Hashimoto's thyroiditis 5.TSH secreting pituitary adenoma 6.Mutation causing activation of TSH receptor EUTHYROID / EXTRATHYROIDAL 1.Iatrogenic
  26. 26. SYMPTOMS           Heat intolerance, fatigability, exertional dyspnea, symptom of vit deficiency, excitability, irritability, nervousness, diarrhea, hyperphagia, thick skin, SIGNS  Thyrotoxic myopathy , weight loss, warm moist skin, tachycardia, high output cardiac failure, fine tremor, exophthalmos, lid retraction, thyroid dermatopathy, thyroid acropathy  NB- Thyroid storms          CLINICAL FEATURE
  27. 27. HYPOTHYROIDISM CRETINISM MYXEDEMA HYPOTHYROIDISM
  28. 28. CRETINISM CAUSES - maternal I2 deficiency, - fetal thyroid dysgenesis, - Inborn errors of TH synthesis, - maternal antithyroid Ab that cross placenta, - fetal hypopituitary hypothyroidism C/F - mental retardation, dwarfism, potbelly, enlarged and protruded tongue, failure of sexual development, cardiac malformation T/t- levothyroxin
  29. 29. CRETINISM
  30. 30. MYXEDEMA CAUSES-Iodine deficiency Autoimmune Iatrogenic Infiltrative disease Pituitary failure Hypothalamic
  31. 31. SYMPTOM Tiredness, weakness, dry skin, feeling cold, hair loss, poor memory, constipation, wt gain, poor appetite, menorrhegia, husky voice SIGN Myxedema, puffy face, cool peripheral extremity, bradycardia, carpal tunnel syndrome, Delayed tendon reflex T/t -levothyroxin
  32. 32. SCREENING OF THYROID DISORDER
  33. 33. THYROID FUNCTION TEST Tests based on primary function of thyroid 1-radioiodine uptake study 2-PBI131 in serum 3.Butanol Extractable Iodine 4.Radioactive Iodine Uptake 3-T3 suppression test 4-TSH stimulation test 5-TRH stimulation test Tests measuring blood level of TH 1-Serum PBI 2-Circulating T4 & T3 level 3-Circulating TSH level 4-Invitro resin uptake of T3 5.plasma tyrosine level Contd
  34. 34.  Tests based on metabolic function of TH 1-BMR 2-Serum cholesterol level 3-Serum creatinine level 4-Blood sugar level Scanning of thyroid gland  Immunological test 
  35. 35. ANTITHYROID DRUGS 1. Drugs inhibit trapping of iodide (I-) - Monovalent anions & metabolic poisons. 2. Thyourylenes - Thyouracil, Carbimazole, Methimazole) 4. Iodine or Iodide 5. β-adrenergic blocking drugs - Propranolol, Atenolol.
  36. 36. THANK YOU
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×