Post on 22-Dec-2015
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
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
Causes of Congenital Hypothyroidism
1. Dysgenesis (85%)
2.Ectopic
3. Enzyme defect (10%)
4. Pituitary, Hypothalamic
5. Iodine deficiency
Congenital Hypothyroidism - Symptoms
• Sleepiness
• Poor Feeding
• Prolonged jaundice
• Constipation
• Hoarse cry
• FHx congenital hypothyroidism
• Maternal history of thyroid disease
Congenital Hypothyroidism - Signs
• Jaundice
• Cold
• Large Tongue
• Coarse facies
• Large fontanelles
• Hypotonia
• Distended abdomen
• Umbilical hernia
• Slow reflexes
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
• 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
• 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
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