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Neonatal Screening for Congenital Hypothyroidism in Preterm Infants: Is a Targeted Strategy Required?
Gerdi Tuli1,2, Jessica Munarin1,3, Kristela Topalli4
1Department of Pediatric Endocrinology, Regina Margherita Children's Hospital, Turin, Italy.
Insights
Neonatal screening for congenital hypothyroidism (CH) in preterm infants is effective, with a 1:156 incidence. The current strategy accurately identifies CH without increasing recall rates compared to full-term infants.
Area of Science:
- Neonatology
- Endocrinology
- Public Health
Background:
- Premature infants face a higher risk of congenital hypothyroidism (CH).
- Neonatal screening strategies for CH in preterm infants require further evaluation.
- Existing screening protocols may not be optimal for this high-risk population.
Purpose of the Study:
- To evaluate the effectiveness of a neonatal screening program for congenital hypothyroidism (CH) in preterm infants.
- To analyze screening results based on birth weight and gestational age.
- To compare recall rates between preterm and full-term infants.
Main Methods:
- Retrospective cohort study of 5930 preterm newborns screened between January 2019 and December 2021 in Piedmont, Italy.
- Thyrotropin (TSH) measurements at 72 hours and 15 days of life.
- Recall criteria: TSH >20 mUI/L at first detection and >6 mUI/L at second detection.
Main Results:
- CH incidence was 1:156, with 76.8% of cases being transient and 87.9% having a eutopic gland.
- Significant differences in mean TSH levels were observed based on birth weight and gestational age at both first and second detections (p < 0.005).
- The 99% reference range in this cohort aligned with recommended TSH cutoffs for screening recall.
Conclusions:
- The current neonatal screening strategy for CH is effective in preterm infants, showing no significant difference in recall rates compared to term infants.
- The screening protocol appears effective in preventing misdiagnosis in preterm neonates.
- Further development and testing of a uniform multinational screening strategy for CH are recommended.
Abstract:
Premature infants are at higher risk of developing congenital hypothyroidism (CH) but the neonatal screening strategy for this population is still debatable. The purpose of this retrospective study is to describe the results of a screening program for CH in a preterm infant cohort. All preterm newborns who underwent neonatal screening in the Italian region of Piedmont in the period January 2019-December 2021, were included in this retrospective cohort study. The first thyrotropin (TSH) measurement was performed at 72 hours, whereas the second at 15 days of life. Infants with TSH >20 mUI/L at first detection and >6 mUI/L at second were recalled for a full evaluation of thyroid function. During the study period, 5930 preterm newborns were screened. Based on birthweight (BW), the mean TSH was 2.08 ± 0.15 for BW <1000 g, 2.01 ± 0.02 for BW 1001-1500 g, 2.28 ± 0.03 for BW 1501-2499 g, and 2.41 ± 0.03 mUI/L in normal-weight newborns (p < 0.005) at the first detection, with a significant difference observed at the second measurement (p < 0.005). Based on gestational age, the mean TSH at first detection was 1.71 ± 0.09 mUI/L for extremely preterm babies and 1.87 ± 0.06, 1.94 ± 0.05, and 2.42 ± 0.02 mUI/L for very preterm, moderately, and late preterm infants (p < 0.005), respectively. Significant between-group differences of TSH measurements were also at the second and third detections (p < 0.005 and p = 0.01). The 99% reference range in this cohort overlapped with the recommended TSH cutoffs for screening recall (8 mUI/L for first detection and 6 mUI/L for second detection). CH incidence was 1:156. Of the 38 patients diagnosed with CH, a eutopic gland was present in 30 (87.9%), with CH transient in 29 (76.8%). We observed no significant difference in the recall rate between preterm and at term infants screened in this study. Our current screening strategy therefore appears effective in avoiding misdiagnosis. CH screening approaches vary among countries. Development and testing of a uniform multinational screening strategy is needed.
