- Remember your thyroid “M&Ms”!
- Thyroid hormones–normal levels vary by age!
- 2014 Pediatrics in Review article
- Epidemiology: ~1:2000-4000
- Common cause of treatable intellectual disability
- Presentation: Few or no symptoms (~95%; hence need for newborn screen)
- Poor feeding, excessive sleepiness, not meeting milestones, edematous, poor tone, enlarged tongue, dry skin, jaundice, anemia
- Causes: thyroid dysgenesis, iodine deficiency (most common cause in developing nations), maternal antibodies (anti-TSHr), medications, TSH receptor dysfunction, and hypothalamic/pituitary dysfunction
- Diagnosis: Newborn screen (NBS) or targeted testing if symptoms present
- Treatment: When NBS is abnormal treat immediately after sending confirmatory testing
- Replace T4 (levothyroxine) orally and refer to endocrinology
- Prognosis: 30% of cases resolve as child grows. Early treatment and identification improves neurocognitive outcomes!
HYPOTHYROIDISM IN CHILDREN & ADOLESCENTS!
- Epidemiology: ~1:1500
- Presentation: declining height velocity, delayed puberty, change in school performance, cold intolerance, depression, carpal tunnel, constipation, weight gain (though less common than adults), edema, HLD, anemia, and hyponatremia
- HLD – caused by decreased lipid clearance
- Hyponatremia – may result from abnormal free water clearance
- Associations: with other diseases: Trisomy 21, Turner syndrome, T1DM, and celiac disease
HYPOTHYROIDISM IN ADULTS!
- 2012 AACE/ATA Clinical Practice Guidelines
- Epidemiology: 1:300
- Female predominance
- Increases in prevalence with age
- Presentation: Everything mentioned previously plus fertility issues and weight changes
- Causes: primary hypothyroidism (autoimmune, radiation, thyroidectomy), medications (lithium, amiodarone, iodinated contrast, and iodine itself), or hypothalamic pituitary axis issues
- Check TSH and free T4
- No need to check anti-TPO or anti-thyroglobulin
- Do not screen asymptomatic patients
- Do not routinely check T3
- T4 (levothyroxine) on an empty stomach
- Dosing is weight-based, age-specific and depends on pt comorbidities
- Recheck TSH six weeks after treatment initiated; adjust dose as needed once TSH normalizes and symptoms resolve; once maintenance dose is established can check labs yearly
- 2019 JAMA review
- Defined as elevated TSH (5-10 uM/L range) in the presence of normal T4
- May be useful to check for TPO antibodies given the 5% risk per year of converting to overt hypothyroidism if antibodies are present (Grade B)
- Should be treated if pt becomes pregnant
- Treat with levothyroxine if TSH >10 because of increased risk for CVD (Grade 2C)
- ACOG and ATA recommend not routinely screening for hypothyroidism (Grade B)
- Women considering pregnancy should have there levothyroxine dose optimized prior to becoming pregnant
- Most women should anticipate having their dose of levothyroxine increased during pregnancy and frequent blood work
WHEN TO REFER?
- Infants and children
- Poor response to therapy
- Thyroid nodule or goiter present
- Planning conception or pregnancy
- Concern for central hypothyroidism
- Have other endocrine disorders like adrenal insufficiency or hypopituitarism
- Congenital hypothyroidism is rare and will resolve ~30% of the time; prompt treatment should be initiated if NBS is abnormal even with confirmatory testing pending
- Check TSH and T4 if exhibiting symptoms (don’t forget HLD). Remember the M&Ms!!!
- Do not screen asymptomatic individuals
- Do not routinely check T3
- Rare in child and adolescents but commonly associated with other disease states diagnosed in this age group like Type 1 DM and Celiac disease
- Not very useful to order TPO antibodies unless pt has subclinical hypothyroidism (increases risk of conversion to over hypothyroidism)
- Levothyroxine dose is weight-based and varies by age and comorbidities (lower doses in elderly and individuals with CAD; higher dose in pregnancy)
*Blog post based on Med-Peds Forum talk by Roger Auth, PGY4