The pediatrician received a telephone call from the state newborn screening program’s pediatric endocrinologist about a 3-day old term male infant whose neonatal screening test for TSH (thyroid stimulating hormone) was high and presumptively positive for congenital hypothyroidism.
The endocrinologist gave the pediatrician specific instructions to re-evaluate the patient, have blood drawn for a free T4 (free thyroxine), TSH and neonatal screening test.
The pediatrician was also instructed to begin the patient on Synthroid® (levothyroxine) 50 micrograms daily orally.
The patient was seen later that day.
His past medical history showed a healthy term male born to a G2P2 mother who had received prenatal care. The intrapartum and post-partum history were negative.
His birth weight was 3570 g and his discharge weight the previous day was 3490 g.
He was breast-feeding every 2-3 hours for 15 minutes and having many diapers with stool and urine.
The family history was negative for endocrine disorders including thyroid disorders. There was a history of stroke.
The review of systems was negative.
The pertinent physical exam showed an alert male with a weight of 3290 g (~25%), height of 51 cm (~50%), and head circumference of 35.5 cm (~50%). The anterior fontanelle was 1×1 cm and soft, and there was minimal jaundice of the face. The rest of his examination was normal.
The laboratory evaluation showed a TSH of 847 micro international units/ml (normal = 0.27-4.20), free thyroxine of 0.43 nano-grams/dl (normal = 0.93-1.7), repeated neonatal screening was again high for the TSH but no other abnormalities.
The diagnosis of congenital hypothyroidism was confirmed and the patient was continued on Synthyroid. At his two week check-up, his weight had increased to 3730g and he appeared normal. He was to follow-up with an endocrinology appointment within the week.
Congenital hypothyroidism used to be a common cause of mental retardation. With the advent of neonatal screening programs and treatment within the first two weeks of life, cognitive development can be normalized.
Usually congenital hypothyroidism is a permanent condition resulting from dysgenesis or agenesis of the thyroid gland. Occasionally it can be caused by a pituitary or hypothalamic abnormality (i.e. secondary or tertiary hypothyroidism).
Occasionally, there can be altered neonatal thyroid function that can be attributed to maternal medication or antibodies, or due to iodine excess or deficiency.
Neonatal screening specimens should be drawn optimally by 48 hours to 4 days of age. Testing in the first 24-48 hours may lead to false-positive TSH elevations using any screening method, but this timing is often used because it is convenient for the families and healthcare providers.
The circles on the approved filter paper forms (i.e. Guthrie cards) need to be filled and saturated to be accurate. The specimens need to be dried at room temperature and should not be subjected to excessive heat.
Neonatal screening programs use one of two basic methods for detection. As there are potential problems in each method, so a pediatric healthcare provider should be familiar with the limitations of each method.
Primary TSH with backup T4 measurements
- Used by most programs in the United States, Canada, Mexico, Japan and Europe
- The test measures TSH and if high, does subsequent T4 measurements
- May miss a delayed TSH elevation in babies with thyroid-binding globulin deficiency, central hypothyroidism and hypothroxinemia
- Delayed TSH elevation is common in low birth weight infants also
Primary T4 backup TSH measurements
- The tests measures T4 and if low, does subsequent TSH measurements
- May detect infants with thyroid-binding globulin deficiency, central hypothyroidism and possibly hypothroxinemia
- Will miss a baby with an initial normal T4 but delayed elevation in TSH
Each state in the United States uses a neonatal screening program to screen for different conditions. A current listing by state and condition can be found at National Newborn Screening and Genetics Resource Center.
The goal of the evaluation and treatment is to normalize the TSH and to maintain T4 and free T4 levels in the upper half of the normal range.
The pediatric health care provider and the pediatric endocrinologist should work together to ensure that proper patient and family education occur along with treatment plan and followup.
- Initial workup – detailed history and physical examination, referral to pediatric endocrinologist, check/recheck serum TSH and free T4, thyroid ultrasonography and/or thyroid scan
- Medication – Levothyroxine10-15 micrograms/kilogram daily by mouth to be begun as soon as the neonatal screening test is presumably positive for congenital hypothyroidism
- Monitoring – recheck T4 and TSH 2-4 weeks after initial treatment is begun, every 1-2 months for first 6 months of age, every 3-4 months between 6-36 months of age and then every 6-12 months until the end of growth
- Monitoring may be more often required if compliance is questionable, abnormalities are found, or the medication source has changed
- Assessment of permanence of the hypothyroidism – congenital hypothyroidism is considered permanent if the thyroid scan/ultrasonography reveals an ectopic thyroid gland or absent tissue, or if the TSH has increased above 10 micro-units/l after the first year of life.
Questions for Further Discussion
1. What are the indications for cord blood screening for congenital hypothyroidism?
2. When should premature infants be screened for congenital hypothyroidism?
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
To view current news articles on this topic check Google News.
Rudolph CD, et.al. Rudolph’s Pediatrics. 21st edit. McGraw-Hill, New York, NY. 2003:2065-69.
American Academy of Pediatrics; Rose SR; Section on Endocrinology and Committee on Genetics, American Thyroid Association; Brown RS; Public Health Committee, Lawson Wilkins Pediatric Endocrine Society; Folly T, Kaplowitz PB, Kaye CI, Sundararajan S, Varma SK. Update of newborn screening and therapy for congenital hypothyroidism. Pediatrics. 2006 Jun;117(6):2290-303.
ACGME Competencies Highlighted by Case
1. When interacting with patients and their families, the health care professional communicates effectivelyeffectively and demonstrates caring and respectful behaviors.
2. Essential and accurate information about the patients is gathered.
3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
4. Patient management plans are developed and carried out.
5. Patients and their families are counseled and educated.
7. All medical and invasive procedures considered essential for the area of practice are competency performed.
8. Health care services aimed at preventing health problems or maintaining health are provided.
9. Patient-focused care is provided by working with health care professionals, including those from other disciplines.
10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.
13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.
23. Differing types of medical practice and delivery systems including methods of controlling health care costs and allocating resources are known.
24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.
25. Quality patient care and assisting patients in dealing with system complexities is advocated.
Donna M. D’Alessandro, MD
Associate Professor of Pediatrics, Children’s Hospital of Iowa
September 11, 2006