Congenital Hypothyroidism: Detection Dilemma

Did you know?
Currently, CH newborn screening is performed in all 50 states, the District of Columbia, Puerto Rico, and the US Virgin Islands. However, each program is allowed to choose their own cutoffs so varied cutoffs means varied outcomes for detection and appropriate follow up care.

What exactly is the dilemma? 

One would think ALL programs would follow the AAP guidelines on Newborn Screening & Therapy for Congenital Hypothyroidism, correct? Unfortunately, many do not because they simply don’t have the funds/resources to detect more than 90% of the permanent (albeit mild) CH cases. Therein lies the dilemma – funding and appropriate continued education for healthcare providers. According to the AAP, “physicians must not relinquish their clinical judgment and experience in the face of normal newborn thyroid test results. Hypothyroidism can be acquired after the newborn screening. When clinical symptoms and signs suggest hypothyroidism, regardless of newborn screening results, serum free thyroxine and thyroid-stimulating hormone determinations should be performed.” 

What are the signs?

The most common neonatal signs of CH are prolonged jaundice, constipation, and umbilical hernia. Other physical findings may include poor growth, goiter, low metabolic rate, constipation, poor peripheral circulation, bradycardia, and myxedema. Research has found infants with these early clinical findings seem to have a higher incidence of developmental disabilities. However, more than 95% of infants with mild or sporadic hypothyroidism show such minimal signs at birth that the diagnosis is missed! 

Why are they missed at a clinical level?

Often, the clinical signs of hypothyroidism (other than neonatal jaundice) may not appear until the infant is several months of age or older. Even more concerning for new parents is that normal newborn screening thyroid test results may also decrease doctor vigilance for clinically symptomatic patients. For most doctors, they simply don’t have the time to spend with their patients OR they are afraid of getting sued for upsetting a parent with a false-positive.

According to the AAP, if the TSH concentration is slightly elevated but less than 40 mU per L, a second screening test should be performed on a new sample. Results should be interpreted using age-appropriate normative values (the TSH reference range at two to six weeks of age, the most common period of retesting, typically is 1.7 to 9.1 mU per L). Approximately 10 percent of infants with confirmed congenital hypothyroidism have TSH values between 20 and 40 mU per L.

Our sons, Micah and Eli, both fell within that ten percent with TSH values of 30 mU per L and 35 mU per L, respectively. Unfortunately, only one of them received appropriate and timely treatment.

How do we solve this detection dilemma?

I think mandatory screening at age 6 weeks would be beneficial – this is currently being done in 9 states and has shown to have the BEST detection of the milder cases of CH including central hypothyroidism which can mean the child’s pituitary gland or hypothalamus is the culprit, however this may not be feasable due to funding as described above.

Shouldn’t legislators demand that State health departments provide better testing and continued education for healthcare providers that is more in line with the AAP guidelines? I think so. Until then, parents and primary care providers should know the signs of CH in children and take action whenever necessary. There is no time to “wait-and-see” with CH.

References: 

http://pediatrics.aappublications.org/content/98/3/473.full.pdf & http://pediatrics.aappublications.org/content/117/6/2290

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