Thyroid hormone is the hormone that’s mainly responsible for controlling the speed of your body’s metabolism. In infants, thyroid hormone is critical for brain development. Your thyroid, a small, butterfly-shaped gland located at the front of your neck under your skin, makes and releases thyroid hormone. It’s a part of your endocrine system.
3. Distrubance in the thyroid hormone leads to thyroid disorders.
Hypothyroidism: decreased level of thyroid hormone
Hyperthyroidism: increased level of thyroid hormone
HYPOTHALAMUS
Thyroid
Releasing
Hormone
(TRH)
PITUTARY
GLAND
THYROID
STIMULATIN
G
HORMONE
(TSH)
THYROID
GLAND
1.Triiodothyr
o-nine (T3)
2.Thyroxine
(T4)
3.Calcitonin
FUNCTION
Increase
metabolism
Increase growth
& development
Introduction
4. Largest endocrine gland.
Located inferior to cricoid cartilage.
Butterfly shaped organ comprising of two lobes:
lobus dexter(right), lobus sinister(left)
Weight 15-25 gm in adult.
Histologically it is made up of follicular (T3 & T4) and parafollicular
(calcitonin) cells.
Functional unit: follicle or acinus
Thyroid Glands
7. Triiodothyronine (T3) Thyroxine (T4)
Release pattern 15% release from glands,rest (85%) is
converted from T4
Mainly release from thyroid glands
Release amount 6ug/day 100ug/day
activity T3 has 3-5 times more active than T4
Half life <1day 5-7 days
Thyroid Hormone
8. Metabolic Function Growth & Developmment
Increase the metabolism of
carbohydrate,protein & lipids.
Increase the production of growth
hormone and potentiating its effects.
Control the activity of other hormone
like insulin,glucagon,glucocorticoids
and acetylcholamines
Important for skeletal development.
Increase the oxygen consumptions
and heat productions.
Essential for normal growth and
maturation of CNS.
Increase the cardiac activity.
Also affect function of kidney, liver
and muscle.
Thyroid Hormone Physiology
10. HYPERTHYROIDISM
Hyperthyroidism or over reactive thyroid causes your thyroid to
produce more thyroid hormone (T3&T4) than demands or needs. This
inhance the metabolic and growth functions of the body.
ETIOPATHOGENES
Graves disease
Toxic adenomas: formation of nodules in the gland and being to
secrete thyroid hormone; some goitre may contains several of this
nodules.
Subacute thyroiditis : inflammation of gland ; “leak’’ excess hormone.
12. Sometimes called Graves’ thyroiditis,
This condiction account for 75% of case of hyperthyroidism.
It affects women 5 to 10 times more than men and may occur at any age, being most
common between the ages of 30 and 50 years.
It is an autoimmune disorder in which an antibody (TSH-Receptor antibody stim)
that mimics the effects of TSH is produced,
causing:
Increased release of T3 and T4 and signs of hyperthyroidism
Goiter (visible enlargement of the gland) as the antibody stimulates thyroid growth.
Graves disease
14. Rarely occurs but life threatening
Sudden and sever exacerbation of hyperthyroidism
Etiology : precipitated by stress or infection with either unrecognised
thyrotoxicosis or inadequately treated thyrotoxicosis, trauma, pregnancy,
emotional stress.
Management
Antithyroid drugs, beta blockers, antibiotics, steroids.
Thyroid strom
15. Hypothyroidism or underactive thyroid is when thyroid gland unable to produce enough
amount of hormone to fulfil the demands.
This slowdown the body metabolic and growth function
Female:Male ratio(6:1)
Primary Hypothyroidism: thyroid can not produce enough hormone as per pituitary
signal. Thyroid failure
Secondary hypothyroidism: thyroid isn’t being stimulated from pituitary to produce
hormone. Pitutary failure
Hypothyroidism
17. Iodine supplements if hypothyroidism occurs due to iodine deficiency
Hormone replacement therapy: synthetic drugs
T4(Levothyroxine): 1.6 ug/kg, aim: to achive normal TSH level (0.4-5.0 mu/L)
T3(Liothyronine):10×more potent
Mixture of T3 & T4 (Liotrix): T4:T3(4:1)
Management
18. Autoimmune lymphatic thyroiditis, described by HAKARU HASHIMOTO
Most common causes of hypothyroidism
Antithyroid antibodies:
Thyroglobulin Ab
Microsomal Ab
TSH-R Ab (block)
Etiopathogenesis: the immune system mistakenly attacks the thyroid and may lead
to damage the throid
HASHIMOTOS THYROIDITIS
19. Hypothyroidism dating from birth (congenital)
Absence of throid hormone results in profound impairment of growth and
cognitive development
Thyroxine is essential for growth and development of brain during the first
three years. Earlier onset greater is the brain damage.
Etiology
Congenital developmental defects
Iodine deficiency
Hashimotos thyroiditis.
Cretinism
20. • Etiology
Severe hypothyroidism in which there is accumulation of hydrophilic
mucopolysaccharides in the skin and other tissues.
Common in women
Two varients
i. Hyperthyroid Myxedema
ii. Hypothyroid Myxoedema
Increased deposition of glucosamine glycans
Myxoedema