Thyroid disease in a child Flashcards
Describe the course of thyroxine in the fetus and after birth.
Fetus - small amount of thyroxine is transferred from mother to fetus (but only severe hypothyroidism will affect the developing brain of the fetus); fetal thyroid makes ‘reverse T3’ which is an inactive T3 derivative.
After birth - surge in TSH occurs, followed by T3 and T4 rise. TSH then declines to normal adult levels within first week of life. Preterm infants will have very low T4 in first few weeks of life and TSH will be within normal range but additional thyroxine is not required.
How common is cogenital hypothyroidism and how is it diagnosed?
Detected as part of neonatal screening as it is common and a preventable cause of learning difficulties - TSH will be raised (except if the cause is pituitary dysfunction as TSH will be normal)
Occurs in 1 in 4000 births
What are the causes of congenital hypothyroidism?
Maldescent of thyroid and athyrosis - most common
Dyshormonogenesis - inborn error of thyroid hormone synthesis, common in consanguinity
Iodine deficiency - worldwide the most common cause
Hypothyroidism due to TSH deficiency - rare and may present with other pituitary dysfunction, micropenis, undescended testes
What are the clinical features of congenital hypothyroidism?
Clinical features are difficult to differentiate from normal in the first month of life but become more prominent later.
- Faltering growth
- Feeding problems
- Prolonged jaundice
- Constipation
- Pale, cold, mottled, dry skin
- Coarse facies
- Large tongue
- Hoarse cry
- Goitre (occasionally)
- Umbilical hernia
- Delayed development
What is the management and prognosis of congenital hypothyroidism?
Treatment with thyroxine should be started at 2-3 weeks of age to aid neurodevelopment. This is lifelong ans should be titrated to maintain normal growth, TSH and T4 levels.
Intelligence should be in normal range for majority of treated children.
What is the most common cause of acquired hypothyroidism in children? Which conditions predispose to acquired hypothyroidism?
- Autoimmune thyroiditis is the most common cause
Increased risk in:
- Down syndrome
- Turner syndrome
- Other autoimmune disorders e.g. vitiligo, RhA, DM, Addison’s disease
Who is more commonly affected by acquired hypothyroidism ?
Females > males
What are the clinical features of acquired hypothyroidism?
- Short stature/poor growth
- Cold intolerance
- Dry skin
- Cold peripheries
- Bradycardia
- Thin, dry hair
- Pale, puffy eyes with loss of eyebrows
- Slow-relaxing reflexes
- Goitre
- Consipaton
- Delayed puberty/amenorrhoea
- Obesity
- Slipped upper femoral epiphysis
- Poor concentration
- Deterioration in school work
- Learning difficulties
What is the most common cause of hyperthyroidism?
Graves disease (autoimmune thyroiditis) secondary to the production of thyroid-stimulating immunoglobulins (TSIs)
Who is more commonly affected by hyperthyroidism?
Teenage girls
What are the presenting features of hyperthyroidism?
Similar to adults but with fewer eye signs.
What do investigations show in hyperthyroidism?
- T4/T3 - elevated
- TSH - suppressed
- Antithyroid peroxismal antibodies - may be present and may subsequently cause hypothyroidism
What is the management of hyperthyroidism and what are the risks associated with treatment?
Carbimazole or propylthiouracil - risk of neutropenia; seek help if sore throat and high fever
Beta-blockers - can be added for symptomatic relief of anxiety, tremor, tachycardia.
Treatment lasts ~ 2 years.
What is the prognosis/complications of hyperthyroidism?
Eye signs may not resolve
40-75% may relapse after treatment is stopped - second course of drugs may be given or surgery/radioiodine treatment.
Hypothyroidism may occur so follow-up is important
What are the complications of transfer of maternal TSI (thyroid stimulating antibodies) from mother to fetus?
May cause neonatal hyperthyroidism which can be fatal so treatment is required until regresssion of TSIs occurs.
