Transcript Thyroid Disease

Thyroid Disease
Embryology
• TG develops from floor of Pharynx at 4 weeks
• travels inferiorly
• thyroglossal tract disappears - cystic elements
may remain as thyroglossal cyst
• Diverticulum becomes bi-lobed & fuses with
ventral aspect of 4th pharyngeal pouch
• Organogenesis under genetic control transcription factors TTF1, TTF2, Pax8 crucial
• Hypothalamus
TRH
• Pituitary
TSH
• Thyroid Gland
Thyroid hormone T4
• Thyroid Gland
95% T4
5% T3
• T4 deiodinated peripherally to
T3
and rT3
Circulating Thyroid Hormones
• 99.5% protein bound
• 0.5% free and active
• Exert negative feedback to hypothalamus
and Pituitary
Thyroid Gland
Controlled by TSH
1. Iodide
2. Iodide
Iodine
3.Iodine + tyrosine mono and diiodotyronine
4. Coupling
T3 and T4
5. Proteolytic enzyme
T4 and T3
Action of Thyroid Hormones
1.Speed up metabolism
2.Essential for: growth
mental development
3.Increased sensitivity of CNS and CVS to
catecholamines
Disorders
Hypothyrodism
Hyperthyroidism
Congenital
Acquired
Congenital Hypothyroidism
Incidence in Europe
1 in 3,500
Illingworth, 1983
Causes of Congenital Hypothyroidism
1. Dysgenesis (85%)
2.Ectopic
3. Enzyme defect (10%)
4. Pituitary, Hypothalamic
5. Iodine deficiency
Congenital Hypothyroidism Symptoms
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Sleepiness
Poor Feeding
Prolonged jaundice
Constipation
Hoarse cry
FHx congenital hypothyroidism
Maternal history of thyroid disease
Congenital Hypothyroidism - Signs
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Jaundice
Cold
Large Tongue
Coarse facies
Large fontanelles
Hypotonia
Distended abdomen
Umbilical hernia
Slow reflexes
Congenital Hypothyroidism
Diagnosis
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TSH
T4 (low or normal)
Xray knee
Technetium scan
Treatment
• L-Thyroxine
• Excess - craniosynostosis
Congenital Hypothyroidism
Prognosis
1.Early treatment screening programme
2.Social class
Hypothyroidism in Older
children
1. Congenital
2. Autoimmune thyroiditis
Hashimoto’s thyroiditis
Associated with other conditions
eg DM, Addisons,Trisomy 21, TS,
3. Post radiation
4. Pituitary, Hypothalamic (TSH level low for FT4)
5. Sick euthyroid syndrome
Hypothyroidism in Older
children - symptoms
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Weight gain
tiredness
constipation
cold intolerance
slowing of growth +/- short stature
? poor school performance
Delayed puberty (occ precocious), irregular periods
History of SUFE, other AI disease
Family history
Hypothyroidism in Older
children - signs
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Myxoedatous facies
short stature
goitre
obesity
delayed reflexes
dry skin
puberty gen delay
Increased body hair
Pallor
Vitiligo
Proximal muscle weakness
Hypothyroidism in Older
children – Diagnosis and
treatment
• FT4 TSH
• TPO
• Thyroxine 100ųg/m2/day
(gradually reach dose)
• ? Other AI disease
• some remit spontaneously
Normal Thyroid Gland
• Not visible
• Barely palpable
Matovinovic, JAMA 1961
Simple or Colloid Goitre
• Clinically euthyroid
• TSH
• T4
• Thyroid antibodies
normal
Neonatal Hyperthyroidism
• Transient
Mother high TSI
• Persistent
Family History of Graves
Hyperthyroidism - Symptoms
1.CNS - nervous, behaviour, poor school
performance
2. GIT - appetite, weight loss, diarrhoea
3. Heat intolerance
TSH suppressed and peferential conversion T4-T3
measure T3
Hyperthyroidism - Signs
1.Eyes
2.Tachycardia
3. Tremor
4. Brisk tendon reflexes
5. Increased growth and bone age
Investigations
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FT4, FT3, TSH
TPO
TRAB
Ultrasound
Technetium Scan
+/- TRH Test
Treatment of Thyrotoxicosis
Carbimazole
Side effects:
rash
arthralgia, SLE
neutropenia
2 year course; 50% remission
Radioactive Iodine
Surgery