Hypothyroidism

Question 1

What are the primary types of hypothyroidism in pediatric patients?

Answer 1

Congenital hypothyroidism and acquired hypothyroidism.

Question 2

What are the common causes of congenital hypothyroidism?

Answer 2

Thyroid dysgenesis, thyroid dyshormonogenesis, hypothalamic-pituitary hypothyroidism, and iodine deficiency.

Question 3

Where is congenital hypothyroidism most common?

Answer 3

In regions where salt is not iodized.

Question 4

What is the most common cause of acquired hypothyroidism in children over 6 years in North America?

Answer 4

Hashimoto’s thyroiditis.

Question 5

What are the key features of Hashimoto’s thyroiditis?

Answer 5

Enlarged and firm thyroid gland, goiter, autoantibodies against the thyroid, and genetic predisposition.

Question 6

What chromosomal disorders are associated with acquired hypothyroidism?

Answer 6

Turner syndrome, Down syndrome, Klinefelter syndrome, and 18p or 18q deletions.

Question 7

What is central hypothyroidism?

Answer 7

A condition where TSH deficiency arises due to hypothalamic or pituitary disorders.

Question 8

How is central hypothyroidism diagnosed?

Answer 8

Low or inappropriate TSH relative to low thyroid hormone concentrations, low FT4, and abnormal TSH circadian patterns with blunted nocturnal surge.

Question 9

What are general symptoms of hypothyroidism in children?

Answer 9

Subnormal growth, delayed bone age, delayed puberty, lethargy, cold intolerance, bradycardia, weight gain, slow speech, dry skin and hair, constipation.

Question 10

What are signs of severe hypothyroidism in children?

Answer 10

Myxedematous features (e.g., periorbital edema, macroglossia), pleural effusion, pericardial effusion, and bowel obstruction.

Question 11

How is primary hypothyroidism diagnosed?

Answer 11

Elevated TSH (>3 mU/mL), low T4, and FT4 concentrations.

Question 12

What is the typical TSH level in central hypothyroidism?

Answer 12

TSH is low, normal, or slightly elevated (<10 mU/L), with FT4 low or in the lowest third of the normal range.

Question 13

What test can confirm central hypothyroidism?

Answer 13

TSH surge test.

Question 14

What is the recommended treatment for hypothyroidism in children?

Answer 14

Levothyroxine therapy.

Question 15

What is the approximate levothyroxine dosage for pediatric patients?

Answer 15

About 100 μg/m² body surface area.

Question 16

How often should thyroid function be monitored after starting levothyroxine therapy?

Answer 16

Every 4-6 weeks after initiation or dose changes, semiannually in children, and annually in adolescents.

Question 17

How should thyroid hormone therapy be adjusted in the PICU for critically ill patients?

Answer 17

Continue therapy; if oral intake is not possible, administer intravenously at approximately two-thirds of the oral dose.

Question 18

Why is monitoring thyroid function important in critically ill pediatric patients?

Answer 18

To recognize and manage primary or central hypothyroidism and adjust therapy in the context of critical illness.

Question 19

What are the hallmarks of congenital hypothyroidism?

Answer 19

Thyroid dysgenesis, dyshormonogenesis, and hypothalamic-pituitary dysfunction leading to low thyroid hormone production.

Question 20

What is the significance of TSH levels in primary hypothyroidism?

Answer 20

Elevated TSH (>3 mU/mL) indicates primary hypothyroidism with reduced thyroid hormone production.

Question 21

How does iodine deficiency cause congenital hypothyroidism?

Answer 21

It impairs thyroid hormone synthesis, particularly in areas without iodized salt.

Question 22

What are the potential complications of untreated severe hypothyroidism?

Answer 22

Myxedema, pleural and pericardial effusion, bowel obstruction, and delayed physical and mental development.

Question 23

What thyroid hormone changes occur in central hypothyroidism?

Answer 23

Low or inappropriately normal TSH with low FT4 concentrations.

Question 24

What are the signs of hypothyroidism that require urgent recognition in the PICU?

Answer 24

Severe lethargy, bradycardia, myxedematous features, and fluid accumulation (pleural or pericardial effusions).

Question 25

How is oral levothyroxine therapy managed if the patient cannot take oral medications?

Answer 25

Administer intravenously at two-thirds of the oral dose.