Hashimoto's thyroiditis is an autoimmune disease that results in the destruction of the thyroid gland and gradual hypothyroidism. It is the most common cause of hypothyroidism in iodine-sufficient areas and typically affects those aged 45-65, predominately women. The thyroid gland may be destroyed through CD8+ cytotoxic T cell killing or cytokine-mediated cell death. Congenital hypothyroidism can be caused by an ectopic thyroid gland, defects in thyroid hormone synthesis (dyshormonogenesis), or mutations in the TSH receptor. Hypothyroidism causes dry, thickened skin and obesity due to a lowered metabolic rate and basal metabolic rate.

1. Hypothyroidism
Causes of dryness and thickness of skin
obesity
Congenital and autoimmune
By Mahdi Saleh

2. Autoimmune
Disorder
Of
Hypothyroidism
Hashimoto disease

3. Autoimmune Disorder Of Thyroid Gland
Hashimoto Thyroiditis
is an autoimmune disease that results in destruction
of the thyroid gland and gradual and progressive
thyroid failure.
The condition was named after
Dr. Hakaru Hashimoto, the doctor
who described it in 1912.

4. Autoimmune Disorder Of Thyroid Gland
Hashimoto Thyroiditis
It is the most common cause of hypothyroidism in
areas of the world where iodine levels are
sufficient.

5. Autoimmune Disorder Of Thyroid Gland
Hashimoto Thyroiditis
It is most prevalent :
45 and 65 years
more common in women
can also occur in children
45-65

7. Autoimmune Disorder Of Thyroid Gland
CD8+ cytotoxic T cell-mediated cell death:
CD8+ cytotoxic T cells may destroy
thyroid follicular cells.

8. Autoimmune Disorder Of Thyroid Gland
Cytokine-mediated cell death:
Activation of CD4+ T cells leads
to the production of
inflammatory cytokines such
as interferon-γ in the thyroid
gland, with resultant
recruitment and activation of
macrophages and damage to
follicles.

9. Autoimmune Disorder Of Thyroid Gland
A less likely mechanism
involves binding of
antithyroid antibodies
(antithyroglobulin, and
antithyroid peroxidase
antibodies) followed by
antibody-dependent
cellmediated cytotoxicity

10. Autoimmune Disorder Of Thyroid Gland
For more information look at:
Robbins and Cotran Pathology
Chapter 24 page 1085-1088

11. Congenital
Of
Hypothyroidism
Introduction To Thyroid
Embryology
congenital cusses

12. Introduction To Thyroid Embryology
The thyroid gland appears
as an epithelial pro-
liferation in the floor of
the pharynx between
the tuberculum impar
and the copula at a
point later indicated by
the foramen cecum

13. Introduction To Thyroid Embryology
Subsequently, the thyroid descends in front of the
pharyngeal gut as a bilobed diverticulum During
this migration, the thyroid remains connected to
the tongue by a narrow canal, the thyroglossal
duct. This duct later disappears.

14. Introduction To Thyroid Embryology
the thyroid gland descends in front of the hyoid
bone and the laryn- geal cartilages. It reaches
its final position in front of the trachea in the
seventh week

15. Congenital Disorder Of Thyroid Gland
Congenital hypothyroidism
is a partial or complete loss of function of
the thyroid gland (hypothyroidism) that
affects infants from birth (congenital)

16. Congenital Disorder Of Thyroid Gland
ectopic thyroid gland
Dyshormonogenesis
TSHR mutation

17. ectopic thyroid gland
Ectopic thyroid is a developmental
defect of thyroid gland that leads
to presence of thyroid tissue at
sites other than its normal cervical
location. It is frequently found
along the course of the
thyroglossal duct. Lingual thyroid
is the most common presentation
of ectopic thyroid

18. TSHR mutation
The TSHR gene provides instructions for making a
protein, known as a receptor, that binds to a thyroid
stimulating hormone (TSH). This receptor spans the
membrane of certain cells (called follicular cells) in
the thyroid gland. A large part of the receptor sits on
the outer surface of the cell (extracellular), and a
small portion is retained inside the cell
(intracellular). Thyroid stimulating hormone binds to
the extracellular portion of the receptor, activating a
series of reactions that control development of the
thyroid gland and its functions.

19. TSHR mutation
Several TSHR gene mutations have been identified in people
with congenital hypothyroidism . TSHR gene mutations
change one of the protein building blocks (amino acids)
used to make the TSHR. Some of these mutations prevent
the receptor from properly spanning the membrane, and in
some cases the entire receptor is retained inside the cell.
As a result, the receptor cannot interact properly with
thyroid stimulating hormone. Other mutations impair the
receptor's ability to bind with thyroid stimulating hormone,
even though the receptor correctly spans the membrane.

20. TSHR mutation
Without properly functioning receptors, thyroid hormone
production is not stimulated. The body tries to correct the
blocked stimulation by producing more TSH . In some cases, the
increased levels of TSH compensate for receptors with minor
defects, and the thyroid functions normally. In other cases,
thyroid hormone levels remain low, causing mild to severe
congenital hypothyroidism. Impaired thyroid stimulating
hormone receptors may also disrupt thyroid development, and
as a result, the gland is smaller than normal. Cases of congenital
hypothyroidism caused by TSHR gene mutations are sometimes
classified as thyroid dysgenesis because development of the
thyroid gland is impaired.

21. Dyshormonogenesis
is a type of primary congenital
hypothyroidism, a permanent
thyroid hormone deficiency that is
present from birth, which results
from inborn errors of thyroid
hormone synthesis.

22. For more information look at:
Langman’s Medical Embryology
Chapter 17page 292-294

23. skin
and
Hypothyroidism
Hashimoto disease

24. Effect Of Thyroid On Skin
Too much thyroid hormone , and skin can
become warm, sweaty and flushed.
Too little thyroid hormone , and skin becomes
dry, coarse, thick and even sweating is
decreased.
Thyroid dysfunction can also lead to thinning
hair and eventual hair loss.

25. Hypothyroidism Skin
In hypothyroidism there is a slow metabolic rate due to alteration of glandular
function. The slowed metabolic function results in insidious onset of
tiredness, fatigue, leg cramps, etc. The skin is cold, dry and pale. The
dryness can be extreme so that there is no sweating and the palms and
soles get thick and dry (keratoderma).
The skin colour can be yellow due to alteration in Vitamin A metabolism
carotenemia.
Hair is lost all over - scalp, groin, even lateral eyebrows. Nails grow slowly and
are brittle and thick.
The most common skin change is a generalized myxedema or swelling due to
a build up of ground substance in the foundation of the skin (dermis). The
skin is swollen, dry, pale and waxy. One can slowly develop a broad nose,
swollen lips and puffy eyelids. Wounds heal slowly

26. For more information look at:

27. obesity
and
Hypothyroidism

28. Relationship between weight and thyroid
Decreased Body Weight. A greatly increased amount
of thyroid hormone almost always decreases body
weight, and a greatly decreased amount of thyroid
hormone almost always increases body weight;
however, these effects do not always occur
because thyroid hormone also increases the
appetite, which may counterbalance the change in
the metabolic rate.

29. Basal Metabolic Rate (BMR).
BMRs are associated with changes in energy
balance
Energy balance reflects the difference between the
amount of calories one eats and the amount of
calories the body uses
high BMR weight loss

30. Relationship between weight and thyroid
The BMR in the patient with
hypothyroidism is decreased
The weight gain not always related
to excess fat accumulation. Most
of the extra weight gained in
hypothyroid individuals is due to
excess accumulation of salt and
water.

31. Guyton And Hall Medical
Physiology
Chapter 77page 956-963
For more information look at:

32. Thank You