Follow up of Infants with Congenital Hypothyroidism Who were Detected by Newborn Screening Test

Kim, Kyung Ah; Lee, Eun Sil; Shin, Son Moon; Moon, Han Ku; Park, Yong Hoon

Abstract

PURPOSE: Developmental delay in congenital hypothyroidism can be prevented by early detection and treatment. We conducted a follow-up study to assess the growth and development of infants with congenital hypothyroidism who were detected by newborn screening test and received thyroid hormone therapy.
METHODS
Nineteen hypothyroid infants were detected by newborn screening test from April 1995 to May 1997. Measurements of free T4 and TSH levels by radioimmunoassay were used as a screening test, and serum T4, T3, free T4, TSH, TBG levels were measured and radioisotope scan of thyroid gland were done for final diagnosis. Height and weight measurements, thyroid function test, and Bayley Scales of Infant Development(BSID II) were done during follow up.
RESULTS
Male to female ratio was 2.2 : 1. The etiologies of congenital hypothyroidism were dyshormonogenesis(7 cases), hypoplasia(6 cases), ectopic gland(5 cases), and aplasia(1 case). All but one infant revealed normal physical growth. Mild developmental delay was detected in five cases by BSID-II about ten months after thyroxine replacement. Two cases revealed mild delay in Mental Developmental Index and 2 cases showed mild delay in Psychomotor Developmental Index, only one case was delayed in both indices. There was a negative correlation between PDI and age of starting treatment(r=-0.505, P<0.05), and a positive correlation between free T4 at the time of diagnosis and MDI(r=0.472, P<0.05).
CONCLUSION
Early diagnosis and treatment were important for normal growth and development of hypothyroid infants, and Bayley developmental scale can be used for long term follow up.