THYROID DYSFUNCTION CAUSED BY MATERNAL AUTOIMMUNE THYROIDITIS: TWO DIFFERENT CLINICAL PICTURES IN TWO SIBLINGS.

Area of Science:

• Endocrinology
• Neonatology
• Immunology

Background:

• Maternal autoimmune thyroiditis can lead to transplacental transfer of antibodies.
• This transfer may cause transient neonatal hyperthyroidism or hypothyroidism in infants.

Observation:

• A rare case of siblings presenting with contrasting thyroid conditions is described.
• One sibling experienced transient neonatal hyperthyroidism, while the other had transient neonatal hypothyroidism.
• Both infants were born to a mother with Hashimoto's thyroiditis.

Findings:

• Neonatal thyrotoxicosis was diagnosed in one sibling, treated with methimazole and propranolol.
• Congenital hypothyroidism was diagnosed in the other sibling, treated with levothyroxine (LT4).
• Both infants were successfully weaned off medication by 5.5 months of age.

Implications:

• Maternal autoantibodies can exhibit variable effects on offspring in different pregnancies.
• Clinicians should consider the potential for diverse neonatal thyroid dysfunction in infants of mothers with autoimmune thyroiditis.
• This case underscores the importance of monitoring infants for thyroid abnormalities following maternal autoimmune thyroiditis.