Objective: To test the hypothesis that very low birth weight (VLBW) and extremely low birth weight (ELBW) infants have an increased incidence of congenital hypothyroidism (CH) with a delayed thyroid-stimulating hormone (TSH) elevation and that the outcomes of these infants are similar to control infants.
Study design: Retrospective analysis of newborn thyroid screening data for 92 800 live births in Rhode Island to identify CH with a delayed TSH elevation. Developmental, growth, and endocrine outcomes of the index cases were assessed at 18 months corrected age.
Results: CH with a delayed TSH elevation occurred in 1 in 58 ELBW, 1 in 95 VLBW, and 1 in 30 329 infants weighing ≥1500 grams (P < .0001). The incidence of head circumference <10(th) percentile was higher in VLBW infants with CH associated with a delayed TSH elevation (P < .05), and the mean head circumferences, weights, lengths, and developmental scores were similar to matched control infants. Three infants received short-term levothyroxine replacement.
Conclusions: The incidence of CH with a delayed TSH elevation was higher in ELBW and VLBW infants compared with infants weighing ≥1500 grams. The outcomes of these infants were comparable with matched control infants.
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