Gallstone formation due to rapid weight loss through hyperthyroidism

Background: Cholesterol metabolism has dramatically changed under hyperthyroid status. However, a combination of hyperthyroidism and cholecystolithiasis is very rare. Case presentation: We report a case of cholelithiasis accompanied by hyperthyroidism in a 13-year-old girl who had recently lost 13 kg of weight (from 53 to 40 kg) in 1 month without loss of appetite. Ultrasonography showed multiple hyperechoic areas with acoustic shadowing in the gallbladder. Thyroid function tests showed that her serum free triiodothyronine (T3) and thyroxine (T4) levels were elevated and the thyroid-stimulating hormone level was decreased. In addition, serum thyrotropin receptor antibody and thyroid-stimulating antibody were detected. The final diagnosis was cholelithiasis with Graves' disease. Thiamazole ingestion was started immediately after the diagnosis, and laparoscopic cholecystectomy was performed 33 days after hospitalization. Conclusions: Massive and sudden weight loss could be a risk factor for gallstone formation in children. In addition, hyperthyroidism has the potential to promote cholelithiasis via cholesterol metabolism.