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Hypothyroidism - Coggle Diagram
Hypothyroidism
Congenital hypothyroidism
relatively common (1 in 4000)
preventable cause of severe learning difficulties
causes
athyrosis
Congenital absence of gland or suppression/ absence of its hormonal secretion
maldescent of gland
commonest
should migrate from sublingual to sublaryngeal
reason why not well understood
dyshormonogenesis
inborn error of thyroid hormone synthesis
5-10% of cases
commoner in consanguinity
iodine deficiency
commonest cause worldwide, uncommon here
prevention = iodination of salt
TSH deficiency
isolated rare
usually a/w panhypopituitarism
hypoglyc
micropenis + undescended testes
clinical features
difficult to differentiate in 1st mo of life, more prominent with age
slight excess of other congenital abnormalities (esp heart)
usually asymp, detected with screening
FTT
feeding problems
prolonged jaundice
constipation
pale cold dry mottled skin
coarse facies (large bulging head, prominent scalp veins, "saddle-like, flat bridged nose with broad, fleshy tip)
large tongue
hoarse cry
goitre
umbilical hernia
delayed development
most detected due to screening
Guthrie test
identifies raised TSH, hence won't detect pit abnormalities (these have low TSH)
Tx = PO thyroxine starting @ 2-3 wks old, lifelong
early tx NB to prevent learning difficulties
with early tx most children will have normal intelligence
Perinatal thyroid hormone production
only small amount of thyroxine transfer from mother to foetus
severe maternal hypothyroidism can affect foetus's brain
foetal thyroid mostly makes 'reverse T3' (inactive)
After birth: TSH surge - T3+4 rises
TSH declines to normal adult levels within 1 wk
Premies have v low T4 for 1st few wks of life but TSH normal - no thyroxine tx needed
Juvenile (acquired) hypothyroidism
usually due to AI thyroiditis
increased in Downs + Turners
increased risk of developing other AI disorders
vitiligo
RA
DM
Addisons
F>M
clinical features
growth failure/short stature
delayed bone age
goitre often present (may actually be physiological in pubertal girls)
cold intolerance
dry skin
cold peripheries
bradycardia
thin dry hair
pale puffy eyes with loss of eyebrows
goitre
slow-relaxing reflexes
constipation
delayed puberty
obesity
SUFE
deterioration in school work + learning difficulties
tx = thyroxine
Exam
inspect for neck swelling
palpate from behind + front for swelling/nodule/thrill
auscultate if enlarged
look for signs of hypo/hyperthyroidism