Rhabdomyolysis in a Young Girl with Van Wyk-Grumbach Syndrome due to Severe Hashimoto Thyroiditis.

Background: Autoimmune hypothyroidism (Hashimoto thyroiditis; HT) is the most common postnatal thyroid disease. Clinical manifestations of HT vary according to disease severity. Due to the pleiotropic effects of thyroid hormone, less common signs and symptoms of HT can occur, leading to a delay in diagnosis. Case presentation: A 9-year-old girl of Indian origin was admitted for a one-week history of widespread myalgia, fatigue, muscle weakness, difficulty walking, and a significant increase in weight (approximately 2 kg) without any changes in daily habits. The only relevant medical history was several intermittent vaginal bleeding episodes since four years of age. Breast development was consistent with Tanner stage 2 without pubic or axillary hair; while height and weight were at the 10th percentile and the 38th percentile; respectively. Bone age from a left wrist X-ray was delayed 1 year. Pelvic ultrasonography revealed a uterine body/neck ratio of >1 (pubertal stage) and multifollicular ovaries. Her external genitalia had a childlike appearance. Laboratory examinations showed an increased thyroid-stimulating hormone, decreased free thyroxine, and positive anti-thyroglobulin antibody titres, as well as elevation of creatine phosphokinase, myoglobin, lactate dehydrogenase, serum aspartate aminotransferase, hypercholesterolemia, and a basal serum prolactin near the upper limit of normal. Follicle stimulating hormone and estradiol were slightly and significantly elevated, respectively. Thyroid ultrasound showed an increased gland size with irregular echostructures and high vascularization. Levothyroxine replacement therapy led to complete normalization of clinical and laboratory findings, including rhabdomyolysis indices. No further vaginal bleeding episodes were reported. Conclusion: This case report highlights how various can be the clinical picture of HT in children, and how rare clinical manifestations can be the only signs of disease at presentation leading to delayed diagnosis and treatment. In this girl, a never-described association of Van Wyk-Grumbach syndrome and acute rhabdomyolysis in a young girl with previously unrecognized HT is described. The importance of recognizing the signs and symptoms of rare complications of HT in order to begin appropriate therapy is stressed.