ESPE Abstracts

Introduction: The prevalence of transient congenital hypothyroidism (TCH) in the Philippines has not been reported in a large-scale study. The diagnosis of TCH remains difficult due to its numerous possible etiologies. Identifying its predictive factors may aid in earlier diagnosis and decreased risk of overtreatment. This study aim ed to determine the predictive factors for TCH in children with congenital hypothyroidism (CH) detected by newborn screening (NBS) in the Philippines from January 2010 to December 2017.

Methods: In this multicenter retrospective cohort study involving 15 NBS continuity clinics in the Philippines, medical records were reviewed and clinical and laboratory factors were compared between children with TCH and those with permanent congenital hypothyroidism (PCH). Of the 2,913 children diagnosed with CH in the Philippines from 2010 to 2017, 1,163 (39.92%) were excluded from the study due to an unrecalled or lost to follow-up status, or a concomitant diagnosis of Down Syndrome.

Results: Among the 1,750 patients included in analysis, 6.97% were diagnosed with TCH, 60.80% were female, mean gestational age at birth was 38 weeks, and mean birth weight was 2,841 grams. Confirmatory thyrotropin (TSH) was lower and confirmatory free thyroxine (FT4) was higher in the TCH group compared to those with PCH (TSH 32.80 vs 86.65 µIU/mL [p <0.0001]; FT4 9.90 vs 7.37 pmol/L [p 0.001]). The TCH group required lower L-thyroxine doses compared to the PCH group at treatment initiation and at 1, 2, and 3 years of age (initial 6.98 vs 12.08 µg/kg/day [p <0.0001]; at 1 year 1.89 vs 4.11 µg/kg/day [p <0.0001]; at 2 years 1.21 vs 3.72 µg/kg/day [p <0.0001]; at 3 years 0.83 vs 3.45 µg/kg/day [p <0.0001]). Among those with TCH, mean serum TSH decreased significantly after treatment with L-thyroxine (32.80 vs. 6.55 µIU/mL, p 0.0001). Other factors associated with TCH were results of thyroid ultrasonography (p 0.007), gestational age at birth (p 0.02), and maternal history of thyroid illness (p <0.0001).

Conclusion: Transient congenital hypothyroidism has a prevalence of 6.97%. Factors associated with TCH are confirmatory TSH and FT4, L-thyroxine dose requirements, thyroid ultrasound findings, gestational age at birth, and a maternal history of thyroid illness.

Keywords: congenital hypothyroidism, Philippines, neonatal screening, prevalence