Download Thyroid Disorders

Dr Malith Kumarasinghe
MBBS (Colombo)
Hormones
Transmit information between cells or organs
Allow adjustment of internal and external
environment
Endocrine organs
Synthesis and release hormones
Maintain homeostatic mechanisms
Endocrine Disorders
 Caused by abnormalities in hormone
Synthesis
Secretion
Control
Function
Common Endocrine Disorders
 Diabetes mellitus
 Thyroid Disease
 Subfertility
 Menstrual disorders
 Osteoporosis
 Short Stature
 Delayed puberty
Thyroid Disorders
Surface Anatomy of Thyroid
Where to look for Thyroid ?
Background
 What: brownish-red, highly vascular gland
 Location: ant neck at C5-T1, overlays 2nd – 4th tracheal
rings
 Avg width: 12-15 mm (each lobe)
 Avg height: 50-60 mm long
 Avg weight: 25-30 g in adults (slightly more in
women)
**enlarges during menstruation and pregnancy**
Thyroid is made up of
 The isthmus
 The lateral lobes
 An inconstant pyramidal lobe
projecting from isthmus
Relations
 Anterior
Pretracheal fascia
Strap muscles
Sternocleidomastoid
Anterior jugular vein
Posterior
Larynx and Trachea
Pharynx and oesophagus
Carotid sheath
Blood Supply
 Arterial
Superior thyroid artery
Inferior thyroid artery
Thyroid ima artery
Venous
Superior thyroid vein
Middle thyroid vein
Inferior thyroid vein
Innervation
Principally from Autonomic Nervous system
 Parasympathetic fibers – from vagus
 Sympathetic fibers – from superior, middle, and
inferior ganglia of the sympathetic trunk
Enter the gland along with the blood vessels.
Recurrent laryngeal nerve
important structure lying between trachea and thyroid
 may be injured during thyroid surgery  ipsilateral vocal
cord paralysis, hoarse voice
Questions
 Components of the thyroid gland?
 Relations of the thyroid gland?
Physiology
 Produces hormones
 thyroxine (T4) and tri-iodothyronine (T3) are
dependent on iodine and regulate basal
metabolic rate
 calcitonin which has a role in regulating blood
calcium levels
THYROID HORMONES
OH
OH
I
I
I
I
I
O
O
NH2
I
O
Thyroxine (T4)
OH
NH2
I
O
OH
3,5,3’-Triiodothyronine (T3)
Thyroid hormones – structure
 Thyroid hormones stored conjugated to thyroglobulin, but




are cleaved by pinocytosis before being released into
circulation
Majority of the thyroid hormone secreted is T4 (90%), but T3
is the considerably more active hormone
Although some T3 is also secreted, most is derived by
deiodination of T4 in peripheral tissues, especially liver and
kidney
Both are poorly water soluble
99% of circulating thyroid hormone is bound to carrier
protein (mostly thyroxine-binding globulin, but also
transthyrein and albumin)
Thyroid hormones – function
 Likely that all cells express thyroid hormone receptors
 Metabolism
 Increases basal metabolic rate
 Increases carbohydrate and lipid metabolism
 Normal growth
 Normal development
 Especially CNS
 Other systems
 CVS – increases heart rate, cardiac output
 CNS – mental acuity
 Reproduction – fertility requires normal thyroid function
Thyroid regulation
www.medscape.com; http://ae.medseek.com/
Thyroid pathology
 Normal thyroid function - ‘euthyroidism’
 Disease states may result in hyper- or hypothyroidism - relative excess or deficiency of thyroid
hormones
 Any swelling of the thyroid may be termed a goitre
 Toxic goitre: associated with increased thyroid hormone
output
 Non-toxic goitre: normal hormone levels
 (Non-specific terms; don’t relate to a particular
pathology)
Epidemiology
http://www.scielosp.org/scielo.php
Hyperthyroidism
Prevalence
Women
2%
Men
0.2%
15% of cases occur in patients
older than 60 years of age
Causes of Hyperthyroidism
Graves Disease – Diffuse Toxic Goiter
Plummer’s Disease
Toxic phase of Sub Acute Thyroiditis
Toxic Single Adenoma
Pituitary Tumours – excess TSH
Molar pregnancy & Choriocarcinoma (↑↑
βHCG)
7. Metastatic thyroid cancers (functioning)
8. Struma Ovarii (Dermoid and Ovarian
tumours)
1.
2.
3.
4.
5.
6.
Graves Disease
 The most common cause of thyrotoxicosis (5060%).
 Organ specific auto-immune disease
 The most important autoantibody is
 Thyroid Stimulating Immunoglobulin (TSI)
 TSI acts as proxy to TSH and stimulates T4 and T3
Toxic Multinodular Goiter (TMG)
 TMG is the next most common hyperthyroidism 





20%
More common in elderly individuals – long standing
goiter
Lumpy bumpy thyroid gland
Milder manifestations (apathetic hyperthyroidism)
Mild elevation of FT4 and FT3
Progresses slowly over time
Clinically multiple firm nodules (called Plummer’s
disease)
Other causes…..
 Sub Acute Thyroiditis (SAT)
 Toxic Single Adenoma (TSA)
Common Symptoms
1.
2.
3.
4.
5.
6.
7.
8.
9.
Nervousness
Anxiety
Increased sweating
Heat intolerance
Tremor
Hyperactivity
Palpitations
Weight loss despite increased appetite
Reduction in menstrual flow or oligomenorrhea
Common Signs
1.
2.
3.
4.
5.
6.
7.
8.
Hyperactivity, Hyper kinesis
Sinus tachycardia or atrial arrhythmia, AF, CHF
Systolic hypertension, wide pulse pressure
Warm, moist, soft and smooth skin- warm
handshake
Excessive perspiration, palmar erythema,
Onycholysis
Lid lag and stare (sympathetic over activity)
Fine tremor of out stretched hands – format's
sign
Large muscle weakness, Diarrhea, Gynecomastia
Thyroid Ophthalmopathy
Proptosis
Lid lag
Onycholysis
Thyroid storm
 Acute, severe, exacerbation of thyrotoxicosis due to acute
serum T3/T4.
 Causes: stressors
 DKA, infection, acute I- tx withdrawal, trauma, thyroid gland
manipulation, radioactive I-, surgery, ether anesthesia.
 Onset: sudden. For surgical pts at risk, it may occur:
 Intraop
 Postop: 6-18hrs.
 Signs
 T, HR, CHF, confusion, shock, death.
Diagnosis
1.
Typical clinical presentation
2.
Markedly suppressed TSH (<0.05 µIU/mL)
3.
Elevated FT4 and FT3 (Markedly in Graves)
4.
Thyroid antibodies – by Elisa – anti-TPO, TSI
5.
ECG to demonstrate cardiac manifestations
6.
Nuclear Scintigraphy to differentiate the
causes
Treatment Options
1.
Symptom relief medications
2. Anti Thyroid Drugs – ATD
 Methimazole, Carbimazole
 Propylthiouracil (PTU)
3. Radio Active Iodine treatment – RAI
Rx.
4. Thyroidectomy – Subtotal or Total
5. NSAIDs and Corticosteroids – for Sub
acute thyroditis
Dietary Advice

Avoid Iodized salt, Sea foods

Excess amounts of iodide in some
Expectorants, x-ray contrast dyes,
 Seaweed tablets, and health food
supplements
These should be avoided because the
iodide interferes with or complicates
the management of both ATD and
RAI Rx.

Hypothyroidism
 1.8% of total population.
 Second only to DM as most common
endocrine disorder.
 Incidence increases with age.
 More common in females.
 2-3% of older women.
Etiology
PRIMARY HYPOTHYROIDISM
 Hoshimoto’s thyroiditis-most common
 Idiopathic hypothyroidism-probably old Hoshimoto’s
 Irradiation of thyroid
 Surgical removal
 Late stage invasive fibrous thyroiditis
 Iodine deficiency
 Drug therapy (Lithium, Interferon)
SECONDARY HYPOTHYROIDISM
 5% of cases.
 Pituitary or hypothalmic neoplasm.
 Congenital hypopituitarism.
 Pituitary necrosis (Sheehan’s syndrome)
Thyroid Failure - Organ Systems
Cardiovascular
• Decreased ventricular contractility
• Increased diastolic blood pressure
• Decreased heart rate
Central Nervous
• Decreased concentration
• General lack of interest
• Depression
Gastro-instestinal
• Decreased GI motility
• Constipation
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Thyroid Failure - Organ Systems
Musculoskeletal
Muscle stiffness, cramps, pain,
weakness, myalgia
 Slow muscle-stretch reflexes,
muscle enlargement, atrophy

Renal

Fluid retention and oedema

Decreased glomerular filtration
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Thyroid Failure - Organ Systems
Reproductive
 Arrest of pubertal development
 Reduced growth velocity
 Menorrhagia, Amenorrhea
 Anovulation, Infertility
Hepatic
 Increased LDL / TC
 Elevated LDL + triglycerides
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Thyroid Failure - Organ Systems
Skin and Hair

Thickening and dryness of skin

Dry, coarse hair, Alopecia

Loss of scalp hair and / or
lateral eyebrow hair
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Clinical Signs of Hypothyroidism
 Coarse Hair; Dry cool and pale skin
 Goitre (not in all cases), Hoarseness of voice
 Non-pitting oedema (myxoedema)
 Puffiness of eyes and face
 Delayed relaxation of Deep tendon reflexes
 Slow hoarse speech and slow movements
 Thinning of lateral 1/3 of eye brows
 Bradycardia, pericardial effusion
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Xanthomata
Tuberous Xanthoma
Xanthelasma
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Myxoedema with Carotineamia
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Hypothyroidism and
Hypercholesterolemia
 14% of patients with elevated cholesterol
have hypothyroidism
 Approximately 90% of patients with overt
hypothyroidism have increased cholesterol
and / or triglycerides
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Thyroid Function Tests
TSH
1.
2. Free T4
3. Free T3
4. Anti-Thyroid Antibodies
5. Nuclear Scintigraphy
6. FNAC of nodule
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Diagnosis
In Primary Hypothyroidism
 TSH is high.
 Free thyroid hormone are depressed.
In Secondary Hypothyroidism
 Both TSH and free thyroid hormones are low.
Anti bodies in hypothyroidism
Anti bodies:
 Anti thyroid peroxidase [ anti microsomal] antibodies
 Anti thyroglobulin antibodies.
 Anti bodies against T3 and T4 in auto immune hypothyroid
disease.
 In primary hypothyroidism;
- up to 12 % pt do have anti gastric parietal cell
antibodies.
- these pts. Can develop pernicious anemia.
Generally…
 Once diagnosis of primary hypothyroidism is made,
additional imaging or serologic testing is unnecessary
if gland is normal on exam.
 In secondary hypothyroidism, further testing with pituitary
provocative testing and imaging to rule out microadenoma.
In general, evidence of decreased levels of more than one
pituitary hormone is indicative of a panhypopituitary
problem.
Treatment-Thyroid Hormone Replacement
 Levothyroxine can cause increases in resting heart rate
and blood pressure
 So replacement should start at low doses in older and
patients at risk for cardiovascular compromise
Monitoring thyroid function
 Most patients can be followed by serial TSH





measurements.
Changes in TSH levels lag behind serum thyroid levels.
So TSH should not be checked sooner than four weeks after
adjusting of doses.
Full effect of replacement on TSH may not become
apparent until eight weeks.
Patients with pituitary insufficiency, T3 and T4 can be
followed.
Goal is to keep thyroid hormone level in middle to upper
range of normal.
Frequency
 TSH or Free T4 monitored yearly.
 No data supports the practice.
 Usually once stable dosage is established, it remains stable
until 60-70 years.
 In elderly serum albumin levels may decrease, so dosage
may have to be decreased by 20%.
 Less frequent monitoring in young patients and annually in
elderly.
Thank
You!