Thyroid Disease in Children docx

Thyroid Disease in Children
Thyroid Disease in Children
Paul
Paul
Hruz
Hruz
MD PhD
MD PhD
Department of
Department of
Pediactrics
Pediactrics
September 2005
September 2005
Introduction
• Thyroid Disease is the Most Common
Endocrinopathy Observed in Children
• While the Disease Processes Present are
Similar to Those in Adults, the Incidences,
Presentations, and Clinical Consequences
Can Differ Markedly
• Failure to Diagnose and Treat Promply May
Lead to Irreversible Neurologic Damage
Lecture Outline
• Disorders of Thyroid Development
• Thyroid Disease in the Newborn
• Hypothyroidism in Children
• Hyperthyroidism in Children
• Thryoid Nodules
Thyroid Physiology of the
Fetus and Newborn

• Normal Thyroid Development
• Thyroid Status in Premature Infants
• Transplacental Passage of Thyroid Ab
• Newborn Screening
• Congenital Hypothyroidism
Thyroid Development
• Orignates from thyroid diverticulum
and ultimobranchial bodies
• Ontogeny influenced by several
transcription factors (TTF, PAX8,
HOX3)
• Largely complete by 10-12 weeks
• Gradual Maturation in Hypothalamic
-Pituitary-Thyroid Axis
Genetic Factors Impacting
Thyroid Development
Fetal Thyroid Maturation
• TSH detectable by 12 wks
• Feedback mechanisms
established by 20 wks
• T3 levels remain low
• Reverse T3 levels high
Placental and Fetal Thyroid
Metabolism
• Independent fetal axis
– Limited T
4
exchange
– Placental type 3 deiodoinase
• Effect of maternal

hypothyroidism
– Most important in first
trimester
• Permeable to TRH, IgG
and thionamides
Thyroid Changes at Birth
• TSH surge at birth
followed by T
4
and T
3
rise
• Important for
interpreting newborn
screen results
• Lower rise in preterm
infants
Cord Blood Thryoid Levels
• Influenced by
gestational age
• Progressive increase
with approach to
term
Thyroid Status in Premature
Infants
• Relative immaturity of axis
• Nadir at 2-3 wks
• Influences
– Illness,
– Iodine exposure,

– T4 clearance,
– Iodine stores
• TSH usually not elevated
Principles of Newborn
Screening
• Relatively High Prevalence
• Deleterious Consequence of
Delayed Diagnosis
• Difficult Clinical Recognition
• Reliable Method of Screening
(sensitive & specific)
• Safe, Effective Treatment
Available
Thyroid Effects in the Fetus
and Neonate
Congenital Hypothryoidism
• Incidence 1:4000
– Slightly higher in female infants
– Higher in Asian babies
– Lower in Black babies
• Primarily Sporadic Occurance
• Overt symptoms may not be present at birth
• Profound effects on brain development
• Reliable testing available (T4 and/or TSH)
• No sequelae if treatment initiated by 4 wks
– 10-15 mcg/kg/d
Etiology of Primary
Congenital Hypothryoidism
• Extensive testing for precise
etiology is generally not

necessary (will not change
immediate care plans)
• May allow assessment of risk
in future pregnancies
• May allow early
determination of transient vs
permanent disease
Transient Congenital
Hypothyroidism
• Defined as abnormal newborn screen with
abnormal confirmatory labs
– 75-80% of abnormal screens due to false +
• Incidence estimated to be ~10% of cases
• Most common in premature infants
•Causes:
– Iodine deficiency or excess
– Maternal antithyroid medication
– Maternal TSH receptor blocking antibodies
Maternal TSH receptor
blocking antibodies
• Incidence estimated at 1:180,000
• Often history of treated Graves in mom
– Mothers may have unrecognized hypothryoidism
• Infant will not have goiter
– Difficult to distinguish from thyroid dysgenesis
• May have permanent neurocognitive deficit if
present in utero
• Resolves in 2-3 months as antibody clears
Treatment Guidelines
• Confirm all abnormal newborn screens with

laboratory TSH and free T
4
– Borderline results may require repeat testing in 2-4
wks
• If repeat labs abnormal, begin thryoxine (25-37.5
mcg/day)
– Goal is to start treatment within first month of life
• Recheck q 2-3 months and adjust dose if
necessary
• If no need to increase dose by 2 ½ -3 yrs, give 4
wk trial off of thyroxine
Hypothyroidism
• Congenital
– Primary
• Thryoid Agenesis
• Dyshormonogenesis
• Iodine Deficiency
– Secondary
• Hypopituitarism
– Isolated
– Multiple hormone deficiency
•Acquired
– Primary
•Surgery
• Radiation
• Autoimmune
• Iodine Deficiency
– Secondary
•Surgery
• Radiation

• Infiltrative
• Tumor
Common Symptoms and Signs
of Hypothyroidism in Children
Growth Failure in Childhood
Hypothyroidism
Hypothyroidism: Treatment
Hashimotos Thyroiditis
• Most common cause of acquired hypothyroidism
• Female:Male (3:1)
• Most children present with asymptomatic goiter
• Clinical Symptoms may be nonspecific
• More frequent in Down and Turner Syndrome
Goiter: Differential Diagnosis
• Congenital
– Dyshormonogenesis
– Maternal Antibodies
• Blocking
•Stimulating
– Maternal Antithyroid drug
• PTU, methimazole
– TSH receptor Activating
Mutation
– McCune Albright Syndrome
–Thyroid Tumor
•Acquired
– Inflammation
– Colloid
– Iodine Deficiency
– Goiterogen

– Infiltrative disease
– Toxic goiter
– Thyroglossal duct
cyst
– Adenoma
–Carcinoma
Endemic Goiter
• Usually euthryoid
• Diffuse gland enlargement
• Rare in US (iodized salt provides adequate iodine
source)
• Rule out autoimmune thyroiditis
• Treament Doses in Children (6-12 months)
– Infants 100 mcg/d
– Children 200 mcg/day
– Adolescents 200-300 mcg/d