Hypothyroidism Flashcards
What are the primary types of hypothyroidism in pediatric patients?
Congenital hypothyroidism and acquired hypothyroidism.
What are the common causes of congenital hypothyroidism?
Thyroid dysgenesis, thyroid dyshormonogenesis, hypothalamic-pituitary hypothyroidism, and iodine deficiency.
Where is congenital hypothyroidism most common?
In regions where salt is not iodized.
What is the most common cause of acquired hypothyroidism in children over 6 years in North America?
Hashimoto’s thyroiditis.
What are the key features of Hashimoto’s thyroiditis?
Enlarged and firm thyroid gland, goiter, autoantibodies against the thyroid, and genetic predisposition.
What chromosomal disorders are associated with acquired hypothyroidism?
Turner syndrome, Down syndrome, Klinefelter syndrome, and 18p or 18q deletions.
What is central hypothyroidism?
A condition where TSH deficiency arises due to hypothalamic or pituitary disorders.
How is central hypothyroidism diagnosed?
Low or inappropriate TSH relative to low thyroid hormone concentrations, low FT4, and abnormal TSH circadian patterns with blunted nocturnal surge.
What are general symptoms of hypothyroidism in children?
Subnormal growth, delayed bone age, delayed puberty, lethargy, cold intolerance, bradycardia, weight gain, slow speech, dry skin and hair, constipation.
What are signs of severe hypothyroidism in children?
Myxedematous features (e.g., periorbital edema, macroglossia), pleural effusion, pericardial effusion, and bowel obstruction.
How is primary hypothyroidism diagnosed?
Elevated TSH (>3 mU/mL), low T4, and FT4 concentrations.
What is the typical TSH level in central hypothyroidism?
TSH is low, normal, or slightly elevated (<10 mU/L), with FT4 low or in the lowest third of the normal range.
What test can confirm central hypothyroidism?
TSH surge test.
What is the recommended treatment for hypothyroidism in children?
Levothyroxine therapy.
What is the approximate levothyroxine dosage for pediatric patients?
About 100 μg/m² body surface area.
How often should thyroid function be monitored after starting levothyroxine therapy?
Every 4-6 weeks after initiation or dose changes, semiannually in children, and annually in adolescents.
How should thyroid hormone therapy be adjusted in the PICU for critically ill patients?
Continue therapy; if oral intake is not possible, administer intravenously at approximately two-thirds of the oral dose.
Why is monitoring thyroid function important in critically ill pediatric patients?
To recognize and manage primary or central hypothyroidism and adjust therapy in the context of critical illness.
What are the hallmarks of congenital hypothyroidism?
Thyroid dysgenesis, dyshormonogenesis, and hypothalamic-pituitary dysfunction leading to low thyroid hormone production.
What is the significance of TSH levels in primary hypothyroidism?
Elevated TSH (>3 mU/mL) indicates primary hypothyroidism with reduced thyroid hormone production.
How does iodine deficiency cause congenital hypothyroidism?
It impairs thyroid hormone synthesis, particularly in areas without iodized salt.
What are the potential complications of untreated severe hypothyroidism?
Myxedema, pleural and pericardial effusion, bowel obstruction, and delayed physical and mental development.
What thyroid hormone changes occur in central hypothyroidism?
Low or inappropriately normal TSH with low FT4 concentrations.
What are the signs of hypothyroidism that require urgent recognition in the PICU?
Severe lethargy, bradycardia, myxedematous features, and fluid accumulation (pleural or pericardial effusions).
How is oral levothyroxine therapy managed if the patient cannot take oral medications?
Administer intravenously at two-thirds of the oral dose.
