15.10.5 Flashcards
Hypothyroidism
- H-P-T axis is failing or in danger of failing o produce sufficient T4.
- Classified according to :
➡️site of abnormality : primary (thyroid), secondary(pituitary) , tertiary (hypothalamus)
➡️severity: compensated or decompensated
➡️onset: congenital or acquired
Congenital hypothyroidism
- One of the more common paediatric endocrinology disorders
- Incidence 1:3500 live births
- Most common preventable cause of learning difficulties
➡️MeanIQ=76 (generalpopulationaverageIQ85-115) - IQ > 85 in 78% of those diagnosed <3months old in 0% if diagnosed >7months old
➡️additional CNS signs include spasticity, tremor, ataxia and
sensorineural hearing loss
Clinical features of congenital hypothyroidism
- Large tongue
- Coarse facies (flat nose, sunken immature nasal bridge)
- Umbilical hernia
- Irritability
- Lethargy
- Poor growth and weight gain
- Short limbs
- Persistently open post.fontanelle, large ant. fontanelle
- Coarse cry
- Pericardial oedema can be noted on echo in infants
left for a prolonged period of time.
Clinical features in the neonatal period:
1.Prolonged gestation
2.LBW (large BW)
3.Persistent jaundice
4.Temperature instability
5.Lag in time to initial episode of stooling to more than 20 hrs after birth (delay passing of meconium)
6.Oedema
7.Hypoactivity
8.Poor feeding
ALL these features are NON-SPECIFIC and may not suggest the specific diagnosis to the physician!
Causes of congenital hypothyroidism
- Thyroid dysgenesis (agenesis, hypoplasia, ectopia) - usually sporadic, but can be familial
- Dyshormogenesis (goitreoften) → inborn errors of thyroid hormone synthesis - Iodine transport defect
- Organification defect
- Pendred s.
- Iodotyrosine deiodinase defect - Thyroglobulin defects (goitreoften)
- mutation of TG gene - Transient Hypothyroidism
- maternal blocking antibodies blocking TSH receptor (mom with auto-immune thyroiditis)
- Goitrogens: medications eg neomecarzole , certain foods - Hypothalamic/pituitaryabnormality
- Rarercauses-endemiccretinism-foundinareaswithiodine
deficient but with supplementation of foods e.g. bread and salt , prevalence has decreased.
Acquired Hypothyroidism
Prevelance
Causes (Primary, Central)
Prevalence:
- 1: 500 school kids
Causes
Primary
- Hashimoto thyroiditis
- I deficiency (endemic cretinism)
- Removal thyroglossal duct cyst
- Goitrogens: XS I, cabbage, soya
- Drugs: Li, amiodarone
- Infiltrations
- Rx for thyrotoxicosis
- Liver haemangioma
Central
- Any acquired HP cause
Clinical Features of Acquired Hypothyroidism
Symptoms
- Cold intolerance
- Weight gain
- Constipation
- Tiredness
- Poor school performance
- Menstrual irregularity
Signs
- Myxoedema (face, wt↑)
- Short/slowing growth
- Goitre
- Dry skin
- Brittle/sparse hair
- Pallor
- Proximal muscle weakness
- Delayed relaxation AJ
- Puberty- delayed/early
Thyrotoxicosis
Causes
Incidence
Causes:
- Graves disease
- Thyroiditis:
➡️ Hashimoto
➡️ Subacute
➡️ Purulent
- Toxic nodule(s)
- Thyroid tumour: Adenoma/CA
- TSH driven: Pit tumour
- Pit resistance to T4
- Activating mutation of TSH receptor
Incidence (Graves)
0.8 : 100 000 kids per year
Clinical Features of Graves Disease
Symptoms:
- Anxious
- Irritable/emotionally labile
- ↓ school performance/handwriting
- LOW
- Rapid height increase
- Heat intolerance
- Palpitations
- Diarrhoea
- Sleep disturbance
- Menstrual irregulation
Signs
- Goitre
- Exophthalmos
- Tachycardia
- Hypertension
- Tremor, choreiform
- Facial flushing
- Sweatiness
- tall stature
- Thyroid bruit
- Heart murmur
Neonatal Thyrotoxicosis
Cause
Prevalence
Clinical
Course
Caues
- Mat TSI (M on Rx or previously Rx)
Prevalence
- GD 1: 2000 pregnancies
Clinical
- Asymptomatic (most)
- Hypothyroid
- Hyperthyroid (<10%) – Mortality <25%
Course
- May start 1-10 days of life
- Self-limiting by 3-12 weeks
