Five-Year Thyrotropin Screening for Congenital Hypothyroidism in Ramathibodi Hospital
PAT MAHACHOKLERTWATTANA, M.D.*, PRAPUTT SIRIPOONY A, M.D.*, PHICHAI THUV ASETHAKUL, Ph.D.****, WINIT PHUAPRADIT, M.D.**, ORAPIN CHAROENPOL, B.Sc. ***, RAJATA RAJATANAVIN, M.D.*****
Affiliation : * Department of Pediatrics, ** Department of Obstetrics and Gynecology, *** Department of Nursing, **** Department of Pathology, ***** Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand.
Objectives : To detect newborns with congenital hypothyroidism (CH) and to treat the
affected infants as early as possible.
Study design : Cord blood thyrotropin (TSH) screening for CH in Ramathibodi Hospital
began in 1993. From October 1993 to December 1998, 35,390 neonates were screened. The infants
with elevated TSH level of greater than 30 mUlL were recalled for verification of CH. Confirma-
tion tests included total thyroxine, free thyroxine and TSH level. Thyroid scan and uptake were
performed in some affected infants.
Results : Twelve infants with CH were detected resulting in an incidence of one in 2,949
live-births. All affected infants were asymptomatic at birth. Of 12 infants with CH, one premature
neonate had a delayed TSH elevation and was diagnosed as having primary hypothyroidism at
2 months of age.
The recall rate for validation of CH based on a cut-off value at serum TSH level of
greater than 30 mUlL is 1.1 per cent. If the cut-off value of serum TSH level was raised to greater
than 40 mUlL, the recall rate would decrease to 0.43 per cent. None of the affected infants had
cord blood TSH level of less than 50 mUlL except one premature patient. Therefore, beginning in
January 1997, the cut-off value of TSH was raised to 40 mUlL or greater.
Pitfalls in this program include incomplete blood-specimen collection and incomplete
follow-up. To strengthen the program, improvements were made in the follow-up system from
1996 onward. Therefore, the coverage for blood-specimen collection progressively increased
from 84 per cent in 1994 to 96 per cent in 1998. Simultaneously, the patients' return after recalls
also increased from 38 per cent to 100 per cent.
Conclusions : The incidence of CH in Ramathibodi Hospital is approximately I:3,000
live-births. The optimal cord blood TSH level for recall is 40 mUlL or greater. The intensification
of follow-up strategy resulted in better response to recall and earlier treatment in the affected
infants.
Keywords : Thyrotropin Screening, Congenital Hypothyroidism, Five-Year at Ramathibodi Hospital
