Delayed Diagnosis of Ectopic Thyroid Due to Ignored Borderline Result of Newborn Screening for Congenital Hypothyroidism

This case report discusses the delayed diagnosis of congenital hypothyroidism in a girl due to a lingual thyroid, where initial newborn screening showed a borderline TSH level of 43.647 mIU/L that was not followed up. Despite early symptoms, her condition was not identified until age 8, when a mass at the base of her tongue was found to be ectopic thyroid tissue. Treatment with levothyroxine improved her symptoms. The report underscores the importance of thorough examination and follow-up in newborns with borderline screening results to prevent delayed diagnosis and treatment of ectopic thyroid conditions, highlighting the need for early identification to avoid complications such as hyperlipidemia and increased cardiovascular risk.