1. Thyroid hormones 3 – the abnormalities Lecture NO: 2nd MBBS
Dr Muhammad Ramzan

2. Abnormalities of TH – the definition
It refers to the ability of thyroid gland to produce its hormones that are either too high or too low for the body requirements
Thyroid gland may be overactive to produce excess or
under active to produce less ones
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3. TH abnormalities --The background
Although THs are not strictly necessary for life, yet they
have profound effects on:
Many physiological processes like body growth, development and metabolism
TH are essential for CNS development in children
Deficiency of TH is not compatible with normal life –

4. TH abnormalities –The types
TH abnormalities may be related either to excess or deficiency and affects all the body cells
These cells are the targets for the thyroid hormones
TH abnormalities occur both in children and adults

5. TH abnormalities – the excess
Excess of TH refers to hyperthyroidism
Thyroid gland is overactive and produces too much TH than body requirements
It is also called as Thyrotoxicosis
Thyroid speeds up body metabolism

6. Hyperthyroidism in general elevated T4/3 ,normal TSH
TH excess is characterized by increase in the :
Basal metabolic rate(BMR),
oxygen consumption and
Heat production through hydrolysis of ATP
There is elevation of FT3 / FT4 with normal TSH

7. Metabolic effects of Thyrotoxicosis 2 types
These are divided into 2:
Hyperthyroid effects
Metabolic effects on Proteins, Lipids and CHO

8. Hyperthyroid effects
Weight loss and cold tolerance due to↑ in BMR /heat production
Warm/ wet hands and high colored skin due to :
hyper dynamic circulation
Rapid pulse, brisk reflexes and peripheral tremors for:
nervous excitation
Bulging and perfused eyes for unknown cause -

9. Perfused skin, eyes and face

10. Hyperthyroidism – Bulging eyes

11. Metabolic effects of hyperthyroidism
Hyperthyroidism affects the metabolism of :
Proteins
Lipids and
Carbohydrates(CHO)

12. Effects on Protein metabolism
Promotes protein breakdown /Proteolysis of Skeletal muscles and releases more AAs in plasma.
Promotes Gluconeogenesis for ↑ in plasma AAs
Proteolysis reduces body weight; muscle weakness, body growth and development in children
Inhibits protein synthesis/ Proteogenesis

13. Effects on Lipid metabolism promotes Lipolysis
TH excess stimulates Lipolysis and ↑ FFAs level
Promotes FA oxidation to generate extra energy
Reduces TG synthesis/ Adipose tissue mass and
Lowers Plasma Cholesterol and TG

14. Effects on Carbohydrate (CHO) metabolism
TH stimulate all the aspects of CHO metabolism and promotes : Intestinal absorption of glucose
Glucose uptake by the body cells and glycolysis
Break down of glycogen – Glycogenolysis
Glycogen synthesis/Glycogenesis and
Gluconeogenesis

15. The deficiency of TH
It is the inability of thyroid gland to produce enough TH for body requirements.
Thyroid gland is under active
The condition is called hypothyroidism or myxoedema
This condition is more common in females

16. Hypothyroidism in general ↑TSH normal FT3/T4
Hypothyroidism results in slowing down of Basal metabolic rate – BMR and reduction in :
Body metabolism; Oxygen consumption and heat
production and hydrolysis of ATP
There is elevation of TSH with normal TF4/FT3

17. Metabolic effects of Hypothyroidism
These are divided into 2:
Hypothyroid effects
Metabolic effects on the Proteins; Lipids and CHOs

18. Hypothyroid effects These include :
Weight gain and non pitting oedema for the S/C deposition of muco polysaccharides/Glycos aminoglyscans /GAGs
Skin is thick; rough, hairless and cold for the hypo dynamic circulation
Face is expression less due to oedema and S/C deposition of GAGs
Pulse/heart rate is slow, reflexes are low and patient is sluggish mentally for the nervous depression

19. Hypothyroidism – Mental sluggishness

20. Hypothyroidism in a female – swollen/ expression less face

21. Non pitting edema of feet

22. Pretibial Myxoedema

23. Hypothyroidism – the metabolic effects
Hypothyroidism affects the metabolism of :
Carbohydrate
Lipids and
Proteins

24. Effects on protein metabolism
Hypothyroidism reduces Proteogenesis and promotes proteolysis especially in skeletal muscles
Excess of glucoplastic amino acids are released from the skeletal muscle break down
These Amino acids are used as substrate for hepatic Gluconeogenesis

25. The deficiency – Effects on Lipid metabolism
Dyslipidemia is commonly observed in hypothyroidism
This includes ↑ in plasma levels of :
TG, Total Cholesterol and LDL- Cholesterol
Low HDL- Cholesterol
Increase in body adipose tissues and reduction in fatty acid oxidation

26. Effects on CHO metabolism
Hypothyroidism suppresses :
All aspects of CHO metabolism
Reduces intestinal absorption of glucose and uptake of glucose by the body cells (Skeletal muscles and Fatty tissues)
Lowers Glycolysis, release of energy and ATP production and body temperature

27. Hypothyroidism - Effects on CHO metabolism cont.
Produces hyperglycemia and Diabetes mellitus
↓ glycogen synthesis (Glycogenesis) and its storage in liver
↑ in the S/C deposition of Glycosaminoglycans/GAGs producing non pitting edema – a hallmark of hypothyroidism

28. Hypothyroidism in infants and children congenital hypothyroidism
Congenital hypothyroidism refers to hypothyroidism
A deficiency or lack of TH at birth
If deficiency of TH is not detected earlier, it will lead to deficiency in IQ and development of CNS

29. Hypothyroidism in infants/ children the presentation
Infants are lethargic,have slow movements and low body temperature
They have big head, protruding tongue , puffy face and feeding problems
Results of treatment are excellent if started earlier

30. Comparison B/W Insulin and Glucagon