Hypothyroidism in First-Degree Relatives of Neonates with Congenital Hypothyroidism: Is there an Association?

Background: Recent studies have shown an increased incidence of congenital hypothyroidism (CH), especially in the middle-east region. The exact etiology is unknown; however, it has been related to several factors, the most noticeable being the high prevalence of transient CH (TCH), parental consanguinity, and the history of hypothyroidism in relatives. We sought to determine the impact of hypothyroidism in the relatives of patients with the observed trend.

Methods: We included all patients with primary CH detected through the Newborn Screening (NBS) Program from 2007 to 2016. We analyzed the impact of consanguinity relationship, parental and siblings' thyroid function, second-degree relatives' thyroid function, parental educational level, age, and maternal gestational diabetes on the development of permanent CH (PCH) and TCH.

Results: A total of 1447 consecutive eligible patients were recruited during the study period. Of this number, 1171 (81%) were diagnosed with CH: 623 (53.2%) had PCH and 548 (46.8%) had TCH. Six hundred thirty-three (54.1%) participants were men, and 814 (69.5%) had a history of relatives' hypothyroidism. Our data analysis revealed a significant difference regarding the male gender, having a history of relatives' hypothyroidism, and parental hypothyroidism compared to TCH ones (P < 0.05). Patients with a history of relatives' hypothyroidism had significantly higher PCH than TCH (P < 0.0001). However, consanguineous marriage was not comparable in patients regardless of their history of relatives' hypothyroidism (P-value >0.884).

Conclusions: Our findings indicated the role of the history of hypothyroidism in neonates' relatives in the evolution of the PCH. Meanwhile, consanguineous marriage did not impress the development of PCH and TCH.