Rhabdomyolysis: A Rare Presentation of Hashimoto Thyroiditis in an Adolescent Boy and Review of the Literature.

INTRODUCTION: Hypothyroidism-induced rhabdomyolysis without precipitating factors is extremely rare, particularly in pediatric patients. We describe a previously healthy adolescent boy who came to our institution with vague symptoms and was found to have rhabdomyolysis secondary to hypothyroidism due to Hashimoto thyroiditis. We also summarize previously published cases in children and adolescents.

CASE PRESENTATION: A 16-year-old boy presented to the emergency department at Riley Hospital for Children with a 2-week history of bilateral eye and lip swelling, fatigue, and slowing of speech initially attributed to angioedema. His laboratory studies were significant for acute kidney injury secondary to rhabdomyolysis. Additional evaluation revealed profound primary hypothyroidism and positive TPO antibodies. Although his free T4 was undetectable, his TSH was only 32.2 mcU/mL. He received IV hydration and thyroid replacement, and his symptoms improved after several months of treatment.

DISCUSSION: Rhabdomyolysis without any risk factors is very rare, especially in children. Our patient was not on any medications, had no family history of neuromuscular disorders, and no history of trauma, infection, or strenuous exercise. The reason behind the disproportionately mild elevation of TSH in the setting of an undetectable free T4 is unclear.

CONCLUSION: It is important for clinicians to be aware that rhabdomyolysis may be a presenting sign of severe hypothyroidism, as delay in diagnosis and treatment can be detrimental.