Objectives: Preterm infants often present CH characterized by delayed TSH elevation. We describe the clinical and biochemical features and the evolution of CH in preterm infants with delayed TSH elevation, detected by the second screening for CH.
Material and Methods: All preterm infants born between 2007 and 2014 negative to the first screening (b-TSH<10 mcU/ml) at 25 days of life and positive to the second screening at 1233 days (b-TSH≥5 mcU/ml), diagnosed with CH and followed-up in a single tertiary Centre of paediatric endocrinology were included. At 23 years, patients with gland in situ (GIS) underwent a clinical re-evaluation including thyroid function testing (TFT) after LT4 therapy withdrawal. According to the result of the TFT after the withdrawal of therapy, patients were divided into 3 groups: permanent CH (TSH persistently>10 mcU/ml), persistent hyperthyrotropinemia (HT) (TSH 510 mcU/ml) and transient CH (TSH<5 mcU/ml).
Results: Forty-six preterm patients were included in the study (26 males, 20 females). Four patients were extremely preterm (<28 weeks), 9 patients were very preterm (2831 weeks), 33 were moderate-to-late preterm (3236 weeks). The sample included 14 twins, 7 patients who were born small for gestational age, 10 cases of syndromes/malformations, 7 cases born after assisted reproduction techniques. Four patients underwent surgery in the neonatal period. At diagnosis, serum TSH was between 1020 mcU/ml in 25 cases, 2040 mcU/ml in 7 cases, 40100 mcU/ml in 6 cases, and >100 mcU/ml in 8 cases (7/8 with very low FT4, range 0.10.44 ng/dl). At diagnosis, the neck ultrasound showed 1 ectopy, 1 hemiagenesis, and 44 cases of GIS. Treatment was started at an average age of 40 days (median 32, range 1589). 37/44 patients with GIS were reevaluated. At reevaluation, 4 patients had permanent CH (TSH after withdrawal of therapy: range 17.8924.07 mcU/ml) requiring the reintroduction of LT4 (10.8%), 10 had HT (27%), 23 had transient CH (62.2%). The 4 permanent cases with GIS were moderate-to-late preterm, 2/4 were twins and in both cases the other twin (not included in the study) had HT. Moreover, they showed only mild TSH elevation at diagnosis (TSH 14.4019.77 mcU/ml).
Conclusions: We confirmed the usefulness of the second-screening strategy for CH to detect preterm infants who otherwise would not be identified at the first screening. Although preterm infants very often have transient CH, many of them may have severe CH at diagnosis, which requires prompt treatment, and some others may have permanent CH (including thyroid dysgenesis), despite mild TSH elevation at diagnosis.
27 - 29 Sep 2018
European Society for Paediatric Endocrinology