Dr: Wael H.Mansy, MD

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Thyroid Disorders
Dr Wael H.Mansy, MD Assistant Professor College
of Pharmacy King Saud University
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Function of the thyroid gland

• There are two main hormones produced by the
  thyroid gland
• Thyroxin (T4) and
• Triiodothyronine (T3).
• Both hormones are derived from the amino acid
  Tyrosine and contain Iodine that is extracted
  from the blood.
• The release of thyroid hormones from the thyroid
  is regulated by TRH secreted from the anterior
  pituitary gland.

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T4 versus T3 T3 5X as active as T4 T4
secreted solely form thyroid gland lt20 T3
secreted from the thyroid gland Majority of T3
from breakdown of T4 (de-iodination) in
peripheral tissue Mostly liver and kidneys
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The main actions of T3 and T4

1. Increased basal metabolic rate
2. Maintenance of normal metabolic function.
3. Normal physical, mental and sexual development.
4. Development of the nervous system in the fetus

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Thyroid Diseases
Definitions Goiter Enlargement of the thyroid
gland Hypothyroidism Inadequate thyroid
hormone production Thyroiditis Inflammation
of the thyroid gland Thyrotoxicosis a term that
is used to describe the toxic effects of excess
thyroid hormones on the body. State resulting
from excess production/exposure to
thyroid hormone Hyperthyroidism
Thyrotoxicosis caused by a hyperfunctioning
thyroid gland Excludes thyroiditis or excessive
exogenous thyroid hormone
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Hypothyroidism
Common causes of Hypothyroidism Thyroiditis
Hashimotos thyroiditis in which antibodies are
produced against the tissue of the thyroid.
Although the exact etiology of this autoimmune
disorder is unknown, it can lead to progressive
destruction of the thyroid gland and loss of
thyroid function. Thyroid Surgery or
Irradiation Iodine deficiency (Goiter) Most
common cause of hypothyroidism worldwide
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Hashimotos Thyroiditis Most common cause of
hypothyroidism Women 30-50 years of age
HLA-DR5 Autoimmune thyroiditis
Antimicrosomal antibodies Against peroxidase
Antithyroglobulin antibodies Against
thyroglobulin Autoantibodies against TSH
receptor Net effect is prevent TSH stimulation
of gland
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Goiter

• Nontoxic goiter
• Hypertrophy of the thyroid gland that is not
  accompanied by excess secretion of thyroid
  hormones.
• May occur as a result of dietary iodine
  deficiency, during pregnancy and at puberty.
• Symptoms are those of hypothyroidism.
• Toxic goiter
• Hypertrophy of the thyroid that is accompanied
  by excess thyroid production.
• May be associated with Graves disease.
• Symptoms are those of hyperthyroidism.

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GOITER
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• Hypothyroidism that occurs during fetal
  development
• May occur as a result of a congenital defect in
  thyroid development
• Severe mental retardation due to poor development
  of the brain
• Poor overall development and growth retardation

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Hypothyroidism
Myxedema

• Hypothyroidism in the adult
• May result from autoimmune destruction of the
  thyroid or thyroid injury or removal
• Presents with signs of hypometabolism including
• Cold intolerance
• Weight gain
• Fatigue
• Bradycardia
• Cool, dry skin
• Anorexia
• Constipation
• Edema of the face (swelling around the eyes),
  hands and ankles drooping eyelids.

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Hypothyroidism
Possible long-term complications of untreated
hypothyroidism cardiac hypertrophy, heart
failure, and myxedema coma, which presents with
hypothermia, seizures and respiratory
depression. Treatment Thyroid hormone replacement
therapy. A variety of synthetic and natural T3/T4
preparations are available for use orally.
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Hyperthyroidism

• Increased synthesis and release of T3 and T4,
  Hyperthyroidism is also referred to as
  Thyrotoxicosis.
• Hyperthyroidism may be
• A primary condition that results from an
  overactive thyroid gland.
• Secondary to excessive stimulation of the
  thyroid by TSH from the pituitary.
• Graves disease the most common causes of
  hyperthyroidism
• Plummers disease toxic goiter not associated
  with Graves disease.
• a tumor of the thyroid. In rare cases carcinomas
  arising outside of the thyroid may produce
  thyroid hormone or TSH.

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Patients with Graves disease produce (Thyroid
Stimulating Immunoglobulin) antibodies that bind
TSH receptors on the thyroid and mimic the
actions of TSH leading to excess production of
thyroid hormones.
Classic Triad (15-20) Diffuse goiter,
Hyperthyroidism, and Ophthalmopathy
(exophthalmos)
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• The manifestations of hyperthyroidism are
  essentially the same regardless of the cause of
  the hyperthyroidism
• Increased basal metabolic rate
• Increased heat production, patient always feels
  hot
• Tachycardia
• Increased catecholamine sensitivity patients
  are at risk for cardiac arrhythmias
• Increased appetite
• Weight loss
• Enhanced bowel activity
• Behavioral changes nervousness and
  hyperactivity

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Laboratory tests to evaluate thyroid function
Serum total thyroxine (total) Unbound or serum
free thyroxine Serum total triiodothyronine
Serum TSH Serum thyroglobulin Antibodies
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Thyroid Antibodies Antithyroglobulin and
Antiperoxidase Markers for Hashimotos but not
specific Thyroid stimulating
immunoglobulinTSI Against the TSH receptor
The cause of Graves disease Predict neonatal
hyperthyroidism
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Thyroid Scan
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• ß-Blocking drugs to blunt the effects of excess
  adrenergic stimulation.
• Antithyroid drugs (propylthiouracil, carbimazole,
  methimazole) that block production of thyroid
  hormone.
• Surgical ablation of a portion of the thyroid may
  be used. Following surgery, patients may likewise
  become hypothyroid and require thyroid hormone
  replacement therapy.

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• Radioiodine Given orally and taken up by
  hormone-producing cells of the thyroid as if it
  were normal iodine. The cytotoxic actions of the
  ß and ? radiation destroy the hormone-producing
  cells of the thyroid. After treatment the patient
  usually becomes hypothyroid and must be managed
  with thyroid hormone replacement therapy.
  Radioactive iodine should not be used in patients
  of childbearing age due to the possible effects
  on offspring.

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Hyperthyroid emergencies Thyroid Storm
Rare complication of hyperthyroidism where
manifestations of thyrotoxicosis become life
threatening. Also may be termed Thyrotoxic
Crisis.
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Precipitating factors Infection
Trauma/Surgery Parturition DKA MI CVA
PE Withdrawal of thyroid meds 20-25 cases no
precipitant found
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Fever gt38.5 Sinus tachycardia out of
proportion to fever. SVT or dysrhythmias with
or without CHF GI symptoms (nausea, vomiting,
diarrhea, rarely jaundice) Volume depletion.
CNS dysfunction (agitation, confusion, delirium,
stupor, coma, seizure)
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