ESPE Abstracts

Aim of the study: The aim of this nationwide population-based register study was to investigate the incidence of congenital malformations, neonatal and chronic comorbidities, and the use of prescribed drugs in patients with primary congenital hypothyroidism (CH).

Methods: The study cohort and matched controls were identified from national population-based registers in Finland (The Social Insurance Institution of Finland and The Finnish Institute for Health and Welfare). All diagnoses from birth until the end of 2018 were collected from the Care Register for subjects born between 1996 and 2018 (cases = 484, controls = 966). Subject-specific prescription drug purchases were identified from The Prescription Register from birth until the end of 2017. The use of antipsychotics and antidepressants was assessed for subjects born between 1987 and 2017 (cases = 566, controls = 1 130).

Results: Newborns with CH were small for gestational age more often than their controls (5.2 %, and 2.2 %, respectively, P=0.002). Neonatal jaundice (12.0 %, and 3.2 %, P < 0.001), hypoglycemia (8.9 %, and 3.7 %, P < 0.001), metabolic acidemia (3.7 %, and 1.1 %, P=0.001), and respiratory distress (6.2 %, and 2.3 %, P < 0.001) were diagnosed significantly more often in newborns with CH than in their controls. Congenital malformations or chromosomal abnormalities were diagnosed in 90/484 CH patients and in 78/966 controls (18.6 %, and 8.1 %, respectively, P < 0.001). The most affected extrathyroidal organs were the circulatory system (8.1 % in CH cases and 3.4 % in controls, P < 0.001) and the musculoskeletal system (5.0 % in CH cases, and 2.4 % in controls, P=0.009). The cumulative incidences of epilepsy (2.3 % in CH patients and 0.3 % in controls, P < 0.001), hearing loss (4.3 %, and 0.6 %, respectively, P < 0.001), disorders in psychological development (14 %, and 4.8 %, P < 0.001), and mental retardation (3.3 %, and 0.4 %, P < 0.001) were significantly higher among CH patients as compared to their controls. ADHD medication was used more frequently by CH patients than their controls (P=0.032) but antidepressant and antipsychotic use was similar.

Conclusions: CH patients have more neonatal morbidity and congenital malformations than their matched controls. The cumulative incidence of neurological diseases, particularly disorders of psychological development, is higher in CH patients. However, our results do not support the existence of severe psychiatric comorbidity.