Transcript to THYROID DISEASES ppt

DISORDERS OF
THYROID HORMONE!
Dr. Ayisha Qureshi
Assistant Professor
MBBS, Mphil
Thyroid hormones are NOT essential for life,
but they do affect the QUALITY of life….
• The main function of thyroid hormones in
adults is to provide substrates for oxidative
metabolism. Thyroid hormones are
thermogenic & calorigenic in nature.
HYPERTHYROIDISM
HYPERTHYROIDISM
Excess (increased) thyroid hormone secretion leads to
Hyperthyroidism
Causes of Hyperthyroidism:
1. Primary Hyperthyroidism:
• GRAVE’S DISEASE
• THYROID ADENOMA
• SUBACUTE THYROIDITIS
• EXCESSIVE INTAKE OF IODINE
• EXCESSIVE INTAKE OF EXOGENOUS THYROID HORMONE
(THYROTOXICOSIS FACTITIA)
2. Secondary:
• Secondary to increased TSH secretion (anterior pituitary
adenoma)
• Secondary to increased TRH secretion (hypothalamic tumor)
GRAVE’S DISEASE
(also
called toxic goitre or
thyrotoxicosis)
It is an autoimmune
disorder in which abnormal
thyroid stimulating
immunoglobulins (TSI)
attach to the TSH receptors
on the thyroid gland.
↓
Diffuse enlargement of the
gland
↓
Stimulation of thyroid
hormone secretion
which suppress the
TSH secretion from
the Ant. Pituitary
↓
↑ levels of TH + Goiter +
Exophathalmos
THYROID
ADENOMA
(also called Nodular toxic
disease or Plummer’s disease)
It is a localized adenoma or
tumor that develops in the
thyroid gland & secretes large
quantities of thyroid hormone.
↓
↑ levels of TH
↓
Signs and symptoms of
Hyperthyroidism
↓
Secretory function of the rest of
the gland is almost totally
inhibited as the thyroid
hormone from the adenoma
depresses the production of
TSH from the anterior pituitary.
CLINICAL FEATURES
Increased metabolism
• Weight loss
• Increased appetite
• Heat intolerance
• Warm moist skin
• Sweating
• Muscle weakness (thyrotoxic
myopathy)
Involvement of CNS
• Irritability/ behavior changes
• Restlessness
• Anger
• Insomnia
• Emotional instability
• Psychosis
• Fine Tremors
• Brisk tendon reflexes
ALL THE PATIENTS OF HYPERTHYROIDISM
CAN PROGRESS TO THYROID STORM IF
LEFT UNTREATED
Involvement of CVS
• Cardiac failure
• Tachycardia
• Atrial fibrillation
• Raised pulse pressure
• Murmurs
Involvement of Reproductive system
• Impotence
• Loss of libido
• Oligomenorhea or polymenorrhea
Eye changes
• Exophthalmos
• Lid lag
Involvement of respiratory system &
GIT
• Breathlessness
• Diarrheoa
Miscellaneous
• Fine, silky hair
• Pretibial myxedema
• Thick brittle nails
GRAVE’S DISEASE
EXPHTHALMOS:
It is the protrusion of the eyeballs.
• Usually seen only with Grave’s disease
CAUSE: Immunoglobulins are found in the blood that react with muscles of the eye
↓
Edema & swelling of retro-orbital tissue
+
Degenerative changes in the extra-ocular muscles
↓
Stare + Lid Lag
↓
Failure of the eye to close completely esp. the upper lid fails to completely close
↓
Dryness of the eye, irritation, infections, pain, double vision
↓
In severe cases, protrusion of the eyeball stretches and damages the optic nerve leading
to BLINDNESS
How will you diagnose
HYPERTHYROIDISM?
Diagnosis of HYPERTHYROIDISM
• ↑ T3 & T4
• ↓ TSH
• ↓ TRH
However, both TRH & TSH will be raised if cause
is excess hypothalamic or pituitary secretion: ↑
T3 & T4 & ↑ TRH & TSH
• Anti-thyroid antibodies
• TSI (Thyroid stimulating Immunoglobulins)
• Scanning images show thyroid tumor if present
TREATMENT
3 options:
1. Anti-thyroid drugs
2. Surgery
3. Radioiodine
ANTI-THYROID DRUGS
All the drugs that cause suppression of Thyroid hormone secretion are called Anti-thyroid
drugs.
1.
-
THIOCYANATE:
Prevent iodide trapping by competitively binding to sodium-iodide symporter instead
of Iodide itself.
Percholate & nitrate ions also follow the same M.O.A.
It can lead to Goiter!!..........HOW?
2.
PROPYLTHIOURACIL: e.g. methimazole, carbimazole
M.O.A: 1: partly blocks peroxidase enzyme
2 : partly blocks coupling
It also causes Goiter as it does not stop synthesis of TG.
3.
IODINE:
If Increased Iodide conc. in the blood (more than 100 times)
↓
Most activities of the thyroid gland are decreased as IODIDE itself inhibits the enzymes
needed for synthesis of TH
↓
Size of thyroid gland & its blood supply decreased
So, Iodine usually given 2-3 weeks before surgery, to reduce the size of the gland
decreasing the necessary amount of surgery & especially the amount of bleeding!!
SITES OF ACTION OF ANTITHYROID DRUGS
HYPOTHYROIDISM
HYPOTHYROIDISM
Decreased secretion of Thyroid hormone is called Hypothyroidism.
1. PRIMARY HYPOTHYROIDISM
(due to primary failure of the Thyroid gland)
• Hashimoto’s Thyroiditis
• Endemic Colloid Goiter
• Idiopathic Non-toxic Colloid Goiter
• Tumors
• Thyroiditis
• Post-surgery
• Post- Irradiation
2. SECONDARY HYPOTHYROIDISM
• Secondary to decreased Hypothalamic secretion
• Secondary to decreased anterior pituitary secretion or Decreased
TSH secretion
3. DUE TO IODINE DEFICIENCY.
CAUSES OF HYPOTHYROIDISM
(Primary causes)
1. HASHIMOTO’S THYROIDITIS:
It is an autoimmune disorder in which, like the Grave’s disease,
there is production of abnormal antithyroid antibodies against the
thyroid follicular cells and the TSH receptors. However, unlike
the Grave’s disease where these antibodies were stimulatory, in
Hashimoto’s disease the antibodies are inhibitory or block the
Thyroid function and destroy the Thyroid gland.
- This process develops very slowly.
- Classical symptoms of Hypothyroidism are seen.
- These patients may also develop other autoimmune
disorders.
CAUSES OF HYPOTHYROIDISM
(Primary causes)
2. ENDEMIC COLLOID GOITER caused by dietary Iodine deficiency in specific areas:
-In areas of Insufficient Iodine in the soil, the food does not contain even the minute quantities
that are required .
-In the absence of iodized table salts, these populations develop very large goiters called
Endemic goiters.
-M.O.A of production of a Goiter:
lack of Iodine
↓
Decreased secretion of T3 & T4
↓
Increased secretion of TSH by the anterior pituitary
↓
Stimulates the thyroid cells to secrete large amounts of TG into the follicular colloid
↓
Gland grows larger & larger
↓
Still no mature hormone, so TSH secretion continues
↓
Stimulus by the TSH continues to stimulate the thyroid cells
↓
Follicles enlarge tremendously & the gland may increase to 10-20 times normal size
CAUSES OF HYPOTHYROIDISM
(Primary causes)
3. IDIOPATHIC NON-TOXIC COLLOID GOITRE:
-
These patients do not have iodine deficiency
The thyroid hormone may be normal or (more frequently) depressed.
- Usually, thyroiditis occurs which is inflammation of some or all of the thyroid
follicles. The inflamed area then becomes replaced by the fibrous tissue and all
secretory activity is lost:
↓
Decreased thyroid hormone secretion from the inflamed areas
↓
Increased TSH secretion from the Anterior Pituitary
↓
Enlargement of the non-inflamed parts of the thyroid gland
↓
Therefore, nodular growth seen
- Also seen in populations eating Goitrogenic foods.e.g. turnips & cabbages
CLINICAL FEATURES
DECREASED METABOLISM
• Weight gain (not burning fuels at a
normal rate)
• Decreased appetite (decreased
BMR)
• Cold intolerance (lack of calorigenic
effect)
• Fatigue (lower energy production)
• Cold peripheries (lower energy
production)
• Thin, dry skin, brittle nails and
thinning hair: All due to effect on
the protein metabolism.
INVOLVEMENT OF CNS
• Mental sluggishness
• Listlessness
• Lethargy & fatigue
• Somnolence
• Psychosis
• Depression
• Poor memory
• Slow reflexes
INVOLVEMENT OF CVS:
• Cardiac failure
• Bradycardia (due to reduction in rate
and strength of cardiac contraction
and a lowered cardiac output)
REPRODUCTIVE SYSTEM
• Loss of libido
• Mennorhagia or oligomenorrhea
GIT
• Constipation
MISCELLANEOUS
• FROG-LIKE HUSKY VOICE
• Deafness
• Loss of eyebrows
MYXEDEMA
CAUSE: In patients with total lack of thyroid hormones, a condition known as
Myxedema develops!!
Patients suffer from all the symptoms of Hypothyroidism and show
following symptoms too:
1. There is characteristic accumulation of a water-retaining complex which
forms the matrix in which other materials are deposited:
Protein+ hyaluronic acid+ chondroitin sulphate
SITE: interstitial spaces, particularly skin.
Because of its osmotic effect, this material causes the water to accumulate in
these spaces, giving rise to the typical non –pitting edema seen in
hypothyroid patients.
2. Atherosclerosis: leading to peripheral vascular disease, deafness &
coronary artery disease & early death.
3. Myxedema coma
4. Myxedema depression
MYXEDEMA COMA
A clinical diagnosis at the end of a hypothryoid continuum. The
patient is usually a case of undiagnosed Hypothyroidism OR
was diagnosed but took no medication.
In such a patient the following symptoms are seen:
–
–
–
–
–
–
Bradycardia, Hypotension
Hypothermia
Hypoventilation
Stupor, Coma
Delayed deep tendon reflexes
Dry, puffy skin
Precipitating Factors:
– Severe Illness
•
•
•
•
Infection
Cerebrovascular Accident
Seizure
GI Hemorrhage
– Surgery
– Sedative Drugs, Anesthetics
Hypothyroidism
Lab studies
• Decreased T4 and T3 levels.
• Increased TSH (If the cause is Primary)
• Presence of antithyroid antibodies (If the
cause is Autoimmune)
• Elevated cholesterol (due to poor
secretion of cholesterol into the bile)
TREATMENT
There is only one treatment which is TH
replacement except when the cause is
Iodine Deficiency in which case IODINE
should be given..
• Thyroxine replacement:
1 daily oral tablet of thyroxine leads to
complete cure!!
• Iodine
CRETINISM
It is a condition in which the infant or the child
has TH deficiency from birth.
CAUSE: extreme hypothyroidism during fetal
life, infancy or childhood.
TYPES:
1. Congenital cretinism (absence of thyroid
gland at birth).
2. Failure of the thyroid gland to produce the
hormone due to a genetic defect. e.g:
PENDRED Syndrome in which the protein
PENDRIN is lacking.
3. Endemic cretinism (iodine lack in the diet)
CRETINISM
• CHARACTERISTICS:
A neonate without a thyroid gland may be of normal appearance &
function b/c he was supplied by the mother in utero!
A few weeks after birth:
- Movements become sluggish
- Physical retardation (skeletal growth more retarded than soft tissue)
- Mental retardation
- Obese
- Stocky
- Short appearance
- Large tongue sometimes to the extent that its huge size obstructs
swallowing & breathing inducing guttural breathing that sometimes
chokes the child.
6 MONTHS OLD BOY with CRETINISM & 4 MONTHS
AFTER TREATMENT STARTED
CRETINISM
TREATMENT:
- Thyroid hormone replacement
immediately within a few weeks as later no
matter how much treatment given then
irreversible, permanent mental retardation!
GOITRE
Large size of the thyroid gland OR thyroid gland
enlargement is called Goitre.
Causes:
1. Physiological: puberty
pregnancy
2. Autoimmune disorder: Grave’s disease
3. Thyroiditis
4. Iodine deficiency goitre (endemic)
5. Goitrogens
6. Tumors
7. Multinodular goitre
GOITER
• CHARACTERISTICS:
It can cause dysphagia & difficulty in
breathing, indicating oesophageal or
tracheal compression!
The patients can show all the symptoms of
Hypothyroidism Or Hperthyroidism
depending on the cause of the goiter!