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Neonatal screening for congenital hypothyroidism using the filter paper thyroxine technique
M P Desai1, P Upadhye, M P Colaco
1Bai Jerbai Wadia Hospital for Children, Bombay.
Insights
This study screened 25,244 newborns for congenital hypothyroidism using filter paper thyroxine (FP-T4). The screening identified 9 cases, suggesting an incidence of 1:2804, highlighting the importance of early detection.
Area of Science:
- Neonatal screening
- Endocrinology
- Pediatric diagnostics
Background:
- Congenital hypothyroidism (CH) is a treatable condition requiring early diagnosis.
- Newborn screening programs are crucial for identifying CH shortly after birth.
Purpose of the Study:
- To evaluate the effectiveness of a filter paper thyroxine (FP-T4) screening protocol for congenital hypothyroidism.
- To determine the incidence of CH in a large cohort of newborns.
Main Methods:
- Screened 25,244 newborns using filter paper thyroxine (FP-T4) at 24-96 hours of birth.
- Recalled neonates with FP-T4 values between 51-80 ng/ml (borderline) and <50 ng/ml (high risk).
- Confirmed diagnosis with repeat FP-T4, serum T4, and TSH levels, supplemented by thyroid scans.
Main Results:
- Confirmed congenital hypothyroidism in 6 newborns via primary screening (incidence 1:4207).
- Identified 3 additional cases missed by primary screening, increasing the probable incidence to 1:2804.
- Follow-up confirmed CH in all 9 infants, with subnormal T4 and elevated TSH levels.
Conclusions:
- The FP-T4 screening protocol is effective in detecting congenital hypothyroidism.
- Early detection and treatment of CH are vital for preventing developmental impairments.
- Refined screening protocols may reduce missed cases and improve diagnostic accuracy.
Abstract:
A total of 25,244 full term consecutive newborns were screened for hypothyroidism at 24 to 96 h of birth using the filter paper technique for thyroxine. The screening protocol based on our pilot study considered filter paper thyroxine (FP-T4) values of 51 to 80 ng/ml (-1 SD) as borderline and < 50 ng/ml (-2 SD) as high risk for congenital hypothyroidism. FP-T4 and/or serum T4 and TSH were reestimated in all neonates with FP-T4 < 80 ng/ml. A total of 4775 (18.9%) newborns (FP-T4, 51 to 80 ng/ml in 4435 and < 50 ng/ml in 340) needed the recall; 2237 (50.4%) with FP-T4 51 to 80 ng/ml recalled by letters and 283 (83.3%) of the 340 subjects with FP-T4 < 50 ng/ml recalled by home visit, responded by 6 wk of age. Congenital hypothyroidism was confirmed in 6 newborns. FP-T4 in one persisted at 55 ng/ml on follow up and in the remainder both initial and repeat values were < 50 ng/ml. Follow up serum T4 values were subnormal (7.8-50.2 ng/ml) and serum TSH elevated (80-1233 IU/ml). Technetium thyroid scan showed agenesis in 3, ectopia in 2 and normal gland with probable dyshormonogenesis in one. Three other newborns (FP-T4 93 to 143 ng/ml) escaped primary detection and were referred later for congenital hypothyroidism. The incidence of congenital hypothyroidism by primary screening was 1:4207 (6 of 25,244) but with these 3 missed cases, probably 1:2804. Congenital hypothyroidism was reconfirmed in all 9 infants between the ages of 2 1/2 to 4 yr.(ABSTRACT TRUNCATED AT 250 WORDS)