Hyperthyroidism, also known as overactive thyroid, results from excessive thyroid hormone production and secretion. Graves' disease, the most common cause, is an autoimmune disorder where antibodies stimulate the thyroid. It is characterized by diffuse thyroid enlargement, ophthalmopathy, and pretibial myxedema. Symptoms include palpitations, heat intolerance, weight loss and tremors. Diagnosis involves low TSH and high T4 levels and presence of thyroid autoantibodies. Treatment options include antithyroid medications, radioactive iodine ablation, or surgery. Thyroid storm is a medical emergency characterized by severe hyperthyroid symptoms that requires urgent beta-blockers, antithyroid drugs and supportive

1. HYPERTHYROIDISM
PRESENTED BY AKUMBA WYCLIFF

2. Introduction:
• The thyroid gland is a butterfly-shaped gland at the front of the neck just below the thyroid
cartilage (Adam’s apple) along the anterior aspect of the trachea.
• It consists of 2 lobes located either side of the trachea connected by an isthmus, each lobe
measuring 4cm long & 2cm wide .
• It is anterior to the trachea between the cricoid cartilage & suprasternal notch.
• Normal gland weighs 10–20grams & receives blood from bilateral superior and inferior thyroid
arteries

3. Physiology
• The thyroid secretes two principle hormones. Thyroxine (T4) - 93% &
triiodothyronine (T3) - 7%. It also secretes calcitonin (responsible for Ca
homeostasis).
• Approximately 85% of T3 in blood is produced from T4 by a family of
monodeiodinase enzymes which are active in many tissues including the liver,
heart, muscles and kidney.
• In peripheral tissues, T4 is converted to T3 by type I deiodinase and by type II
deiodinase in the brain. Type III deiodinase enzyme converts T4 to another
inactive metabolite called reverse T3 (rT3)
• T3 and T4 circulate in plasma almost entirely (99%) bound to transport
proteins, mainly thyroxin binding globulin (TBG). The 1% is of thyroid hormone
freely circulates and is responsible for its effects.

4. HORMONE SYNTHESIS
• Dietary iodine in the form of iodide or iodate is absorbed by the
gastrointestinal tract and distributed in the extracellular fluid
• Circulating iodide is actively transported into the thyrocyte by the sodium-
iodide symporter
• Within the thyrocyte, iodide is rapidly oxidized by H2O2 in a reaction
catalyzed by thyroid peroxidase.
• The reactive intermediate formed is covalently bound to tyrosyl residues
present in thyroglobulin to generate monoiodotyrosine and diiodotyrosine
residues
• Which are combined to form T4 and T3

5. SYNTHESIS OF THYROID HORMONE

6. Regulation of thyroid hormone
• Thyroid hormone secretion is regulated by the hypothalamo-pituitary-
thyroid axis through stimulatory actions of Thyrotropin-releasing hormone
(TRH) and Thyroid Stimulating Hormone (STH).

7. ACTION OF THYROID HORMONE
• Thyroid hormone binds receptors nuclear receptors (α1, β1, and β2)
• in liver, T3 increases expression LDL receptor, resulting in accelerated
LDL clearance.
• In myocardium, T3 increases myocyte contractility and relaxation
• In the cardiac conducting system, T3 increases the heart rate by
accelerating sinoatrial node depolarization and repolarization.
• increases in basal metabolic rate, mental alertness, ventilatory drive,
gastrointestinal motility, and bone turnover.
• During fetal development, thyroid hormone plays critical roles in brain
development and skeletal maturation

8. HYPERTHYROIDISM
• Hyperthyroidism also known as overactive thyroid is a pathological
disorder that involves excessive synthesis and secretion of thyroid
hormone by the thyroid gland.
• Hyperthyroidism results from excessive thyroid function, differentiating it
from thyrotoxicosis which is the clinical syndrome of excess circulating
thyroid hormones, irrespective of the source.
• Hyperthyroidism is common, affecting about 2–5% of all females at some
time and with a female to male sex ratio of 5 : 1, most often between the
ages of 20 and 40 years.

9. SIGNS AND SYMPTOMS

10. ON EXAMINATION
GENERAL APPERANCE
Hyper thyroid face
HANDS
• Warm and sweaty palms
• Tremor, onycholysis/plumber’s
finger(separation of the distal end of the nail)
ARMS
• Pulse; tachycardia, irregular pulse
• Palmar erythema
• Proximal myopathy
• Brisk reflexes
EYES
• Exophthalmos; sclera visible below cornea
• Lid retraction; sclera visible above cornea
• Conjunctiva; chemosis
• Lid lag
NECK
• Look for thyroid enlargement, scar of surgery
• Palpate thyroid, auscultate for bruits
• Pemberton’s sign
CHEST
• Gynecomastia in males
• Ejection systolic murmur
• Signs of cardiac failure
LEGS
• Pretibial myxedema; bil. Firm, elevated
dermal nodules which can be pink, brown due
to mucopolysaccharide accumulation
• Hyperreflexia

11. AETIOLOGY
1. Graves’ disease – 76%
2. Toxic Multinodular Goitre – 14%
3. Toxic adenomas – 5%
4. Thyroiditis
5. Treatment induced - Amiodarone

12. GRAVES’ DISEASE
• This is autoimmune disorder is the most common cause of
hyperthyroidism and accounts for 60–80% of all thyrotoxicosis cases.
• More common in females than males and more common between 20-
40 years of age.
• Reflects a genetic factor with 15% of patients with Graves’ disease
having a close relative with the same disorder.
• It is associated with other autoimmune conditions e.g Type 1 DM,
Pernicious anaemia, Rheumatoid arthritis, Myasthenia gravis, Adrenal
insufficiency.
• High iodine intake is also associated with an increased prevalence of
Graves’ disease.

13. Pathogenesis of Graves’ Disease
• In Graves’ disease, Serum IgG antibodies bind to TSH receptors in the
thyroid, stimulating thyroid hormone production, i.e. they behave like TSH.
These antibodies are called Thyroid - stimulating antibodies (TSAbs).
• These antibodies are specific for Graves’ disease and can be measured in
serum.
• They are present in 85–90% of cases and decline with treatment. Persistent
high levels predict a relapse when drug treatment is stopped.
• There is an association with HLA-B8, DR3 and DR2 and a 50% concordance
rate amongst monozygotic twins with a 5% concordance rate in dizygotic
twins.

14. RISK FACTORS
1. Family history
2. Gender - females are more at risk
3. Age - more common in people of 20 – 40 years of age
4. Other autoimmune disorders – increased risk in other autoimmune
disorders like tpe 1 DM, rhemautoid arthritis
5. Emotional or physical stress
6. Pregnancy
7. smoking

15. CLINICAL FEATURES OF GRAVES’ DISEASE
Graves’ disease is distinguished from other causes of hyperthyroidism by the
presence of three clinical features:
1. Diffuse thyroid enlargement (thyroid goitre)
• In Graves’ disease, the thyroid is usually diffusely enlarged to 2-3
times its normal size.
• The consistency is firm, but not nodular. There may be a thrill or bruit,
best detected at the inferolateral margins of the thyroid lobes, due to
the increased vascularity of the gland and the hyperdynamic
circulation.

16. 2. Ophthalmopathy (eye changes)
• Upper eye lid retraction (Dalrymple sign)
• Lid lag (Von Graefe sign)
• Staring appearance (Kocher sign)
• Chemosis
• Conjuctivitis
• Periorbital edema
• Proptosis
• Diplopia/extra ocular muscle dysfunction
• Impaired visual acuity/fields
• Corneal ulceration
• Grittiness/increased tear production

17. Exophthalmos/proptosis
Staring appearance
Chemosis/periorbital swelling/conjuctivitis

18. Abridged classification of eye changes of Graves’ disease
• Eye features: Classes 0-6, mnemonic “NO SPECS”
• Class 0: No physical signs or symptoms
• Class 1: Only signs, no symptoms (signs limited to upper eyelid retraction, stare and lid lag)
• Class 2: Soft tissue involvement (signs and symptoms - periorbital edema, congestion or
redness of the conjunctiva, and chemosis)
• Class 3: Proptosis (measured with Hertel exopthalmometer)
• Class 4: Extraocular muscle involvement
• Class 5: Corneal involvement
• Class 6: Sight loss (optic nerve involvement).

19. 3. Thyroid dermopathy (pretibial myxedema):
• Thickening of the skin especially over the lower tibia
• It may involve the entire leg and may extend onto the feet
• Skin cannot be picked up between the fingers
• Rare, occurs in 2-3% of patients
• Usually associated with opthalmopathy and very high TSH-R Ab.

20. Other clinical features of Graves’ Disease…
Clinical features:
• Heat intolerance
 Cardiovascular:
• Palpitation, Atrial fibrillation
• CHF, dyspnea, angina
• Gastrointestinal:
• Weight loss, appetite
• Diarrhea
• Reproductive:
• amenorrhea,
• oligo- menorrhea,
• infertility
• Gynecomastia
• Bone:
• Osteoporosis
• Thyroid acropachy
• Neuromuscular:
• Nervousness, tremor
• Emotional lability
• Proximal myopathy
• Myasthenia gravis
• Hyper-reflexia, clonus
• Periodic hypokalemic
paralysis
• Skin:
• Pruritus
• Onycholysis
• Vitiligo, hair thinning
• Palmar erythema
• Spider nevi.

21. Diagnosis of Graves’ Disease
INVESTIGATIONS
• Low TSH levels in blood
• High levels of free T4 in
blood
• Presence of Thyroid
auto antibodies (TSI &
TBII)
• Nuclear thyroid
scintigraphy (I123, Te99)
Radioiodine uptake test

22. MANAGEMENT OF GRAVES’ DISEASE
1. Beta-blockers for symptomatic control
• May need higher doses than normal (Propranolol 40–80 mg every 6–8 hours).
• These don’t stop thyroid hormone synthesis but help to regulate the heart rate
and protect the heart until other hyperthyroidism Tx take effect.
2. Antithyroid drugs
• The most commonly used are carbimazole and its active metabolite,
methimazole. Propylthiouracil is equally effective.
• These drugs reduce the synthesis of new thyroid hormones by inhibiting the
iodination of tyrosine.
• Carbimazole also has an immunosuppressive action, leading to a reduction in
serum TSH-R Ab concentrations, although this action is not effective enough in
this management.

23. Contd…
• Antithyroid drugs should be introduced at high doses (carbimazole 40–60
mg daily or propylthiouracil 400–600 mg daily).
• Usually, this results in subjective improvement within 10–14 days and
renders the patient clinically and biochemically euthyroid at 6–8 weeks.
• At this point, the dose can be reduced and titrated to maintain T4 and TSH
within their reference range.
• In most patients, carbimazole is continued at 5–20 mg per day for 12–18
months in the hope that remission will occur.

24. 3. Thyroid surgery
• Traditionally, a ‘subtotal’ thyroidectomy is performed, in which a portion of
one lobe of the thyroid is left in situ, with the aim of rendering the patient
euthyroid.
• While complications of surgery are rare and 80% of patients are euthyroid,
15% are permanently hypothyroid and 5% remain thyrotoxic.
4. Radioactive iodine
• Single dose of radioactive iodine in pill or liquid form. Over 2–3 months,
radiation slowly destroys thyroid gland cells. As the thyroid gland shrinks, the
hormone levels return to normal. Contraindicated in pregnancy and
breastfeeding.
• Hypothyroidism is a common complication however its easier to manage and
causes fewer long term problems than hyperthyroidism.

25. TOXIC ADENOMA
• This is a solitary, autonomously functioning thyroid adenoma.
• Patients usually > 40years with a noted recent growth of a long-standing
thyroid nodule.
• Thyrotoxic symptoms are present but no infiltrative opthalmopathy.
• Physical exam reveals a nodule on one side.
• Lab tests reveal Low TSH, high T3, slightly high T4
• Thyroid scan reveals “hot” nodule with suppressed uptake in contralateral
lobe.
• Always follicular adenomas and almost never malignant.
• Radioiodine ablation is usually the treatment of choice.

26. Toxic Multinodular Goiter (Plummer’s disease)
• Usually occurs in older patients with long-standing MNG
• PE reveals a MNG that may be small or quite large
• RAI scan reveals multiple functioning nodules in the gland or patchy
distribution of RAI.
• Hyperthyroidism in patients with MNG can often be precipitated by iodide
intake “jod-basedow phenomenon”.
• Amiodarone can also precipitate hyperthyroidism in pts with MNG
• Treatment:
• Same as for Grave’s disease.
• Surgery is preferred.

27. Subacute Thyroiditis
• Acute inflammatory disorder of the thyroid gland most likely due to viral
infection.
• Usually resolves over weeks or months.
• In general, the following 3 forms of Subacute thyroiditis are recognized:
Subacute granulomatous thyroiditis also known as subacute painful
or de Quervain thyroiditis,
Subacute lymphocytic thyroiditis also known as subacute painless
thyroiditis,
Subacute postpartum thyroiditis

28. Subacute Thyroiditis…
• Subacute granulomatous thyroiditis is the most common cause of a painful
thyroid gland.
• This condition is also known as migratory thyroiditis (because the pain can
shift to different locations in the thyroid).
• It is a transient inflammation of the thyroid.

29. Subacute Thyroiditis…
Symptoms & Signs:
• Fever, malaise, and soreness in the neck
• Initially, the patient may have symptoms of hyperthyroidism with palpitations,
agitation, and sweat.
• PE: Thyroid gland is exquisitely tender with no signs of local redness or heat
suggestive of abscess formation.
• Signs of thyrotoxicosis like tachycardia and tremor may be present.

30. Subacute Thyroiditis…
Lab:
• Initially, T4 & T3 are elevated and TSH is low, but as the disease progresses
T4 & T3 will drop and TSH will rise.
• RAI uptake initially is low but as the patient recovers the uptake increases
Management:
• In most cases only symptomatic Rx is necessary (Acetaminophen 0.5 g four
times daily).
• NSAID or Prednisone 20mg three times daily for 7-10 days may be necessary
to reduce the inflammation.
• L-thyroxine is indicated during the hypothyroid phase of the illness.
• 10% of the patients will require L-thyroxine long term.

31. Drug-induced hyperthyroidism
• Amiodarone is a commonly used antiarrhythmic agent that is structurally
related to thyroid hormone (contains 39% Iodine)
• Thus, typical doses 200 mg/d are associated with very high iodine intake
• Management
• Stop the drug if possible, though often impractical because of the
underlying cardiac disorder
• Discontinuation will not have an acute effect because of its storage in
adipose tissue & prolonged half-life
• High doses of antithyroid drugs

32. Thyroid crisis or ‘thyroid storm’
• This rare condition, with a mortality of 10%, is a rapid deterioration of
hyperthyroidism with hyperpyrexia, severe tachycardia, extreme restlessness,
cardiac failure and liver dysfunction.
• It is usually precipitated by stress, infection or surgery in an unprepared
patient, or radioiodine therapy. With careful management it should no longer
occur and most cases referred as ‘crisis’ are simply severe but uncomplicated
thyrotoxicosis.
• Treatment is urgent. Propranolol in full doses is started immediately together
with potassium iodide, antithyroid drugs, corticosteroids (which suppress
many of the manifestations of hyperthyroidism) and full supportive measures.
• Control of cardiac failure and tachycardia is also necessary.

33. Contd…
Specific Measures:
• Propylthiouracil (PTU) is the anti-thyroid drug of choice : 1000 mg Orally.
• If PTU unavailable can give methimazole 30mg p.o. every 6 hours.
• One hour after the loading dose of PTU is given, give iodide which acutely
inhibits release of thyroid hormone (Lugol’s solution 2-3 drops 8h OR potassium
iodide (SSKI) 5 drops q 8h).
• Dexamethasone 2 mg IV 6h for the first 24-48 hours lowers body temperature
and inhibits peripheral conversion of T4-T3 .
• With these measures the patient should improve dramatically in the first 24
hours.
• Identify and treat precipitating factor.

35. References…
• Davidson Principles and Practice of Medicine 23rd Edition
• Kumar and Clarks Clinical Medicine 9th EDition
• www.Mediscape.com