Pediatric thyroid Flashcards
When does the thyroid develop? What else develops with it?
1st Trimester (0 – 13 weeks): hypothalamus, pituitary, thyroid organ development. 2nd Trimester (14 – 27 weeks): functional differentiation: hypothalamic-pituitary-thyroid axis
Embryological origins of thyroid?
originates around pharyngeal arches from esophagus, forms thyroglossal duct, which later atrophies, thyroid migrates down throat
What can cross the placenta (wrt thyroid etc)?
Iodide passes freely, TSH does not, T4 does a little bit.
Fetal thyroid levels.
early is just mother’s thyroid hormones, then fetus starts. T4 is low until late pregnancy. T3 is low throughout.
What happens with the newborn thyroid levels (ie just after birth)?
TSH spike in response to stress (birth, cooler), and T4 jumps up too. Critical for organ differentiation (liver, brain etc) and survival.
What is congenital hypothyroidism?
A developmental defect. Thyroid agenesis/dysgenesis (didn’t develop or didn’t normally). Ectopic thyroid (doesn’t migrate down throat). Thyroid dyshormonogenesis (rare).
Other causes of hypothyroidism?
Rarer in NA. Transient - maternal drugs, iodine deficiency, antibodies (TSH blocking). Secondary-Tertiary Hypothyroidism (hypothalamic-pituitary dysfunction)
How do we screen for congenital hypothyroid?
Test some blood from ankle, take to lab. Needs to be treated immediately!
Signs and symptoms of congenital hypothyroidism
Symptoms: Often none initially, Lethargic, Poor feeding, Constipation. Signs: Maybe none early, Puffy face, Large posterior fontanelle, Macroglossia, Jaundice, Umbilical hernia, Hypotonia
How do you treat congenital hypothyroidism?
L-thyroxine (10-15 µg/kg). Treatment needs to be started early, Follow-up TSH every 1 - 2 months initially, will be lifelong condition. Late treatment results in irreversible brain damage; Early treatment and normalization of TSH during follow-up produces normal development and growth
Neonatal hyperthyroidism
Can be caused be TSH-R IgG that cross placenta (can still be there even if mother was treated for hyperthyroid). Baby can clear the Ab eventually but may need some anti thyroid Tx first.
Signs and symptoms of neonatal hyperthyroidism
Symptoms: Irritability, Voracious appetite, Poor weight gain. Signs: Fetal/postnatal tachycardia, Goitre, Eye signs of hyperthyroidism (stare), Heart failure
Acquired primary hypothyroidism in children?
Very similar to adult. Most commonly autoimmune; incidence increases with age; females>males; often family history of hypothyroid or other autoimmune; increased risk if: other autoimmune disease, Trisomy 21, sex chromosome anomaly
Signs and symptoms of autoimmune hypothyroidism in children
Symptoms: Insidious - often none - they don’t really realize the change like adults do, Lethargy, Altered school performance, Decreased appetite but still gain weight. Signs: Goitre, Decreased height growth, delayed puberty, “Dull” expression, Bradycardia, low pulse pressure, Slow reflex relaxation
How do you diagnosis autoimmune hypothyroidism in kids?
Diagnosis: elevated TSH, positive thyroid peroxidase antibodies. Treatment: L-thyroxine
