Superior mesenteric artery (SMA) syndrome is a rare condition resulting in small bowel partial or complete obstruction. The third part of the duodenum becomes compressed between the aorta and the SMA once a subject loses weight rapidly. The patients at risk of SMA syndrome are those with eating disorders, trauma and substance abuse. We present a case of a 13 - year old female that complained of jaundice 3 months earlier, of recurrent attacks of vomiting and progressive weight loss. The vomiting was bilious and non-projectile following meals, 3-4 times per day. Upon presentation her weight was below the third percentile for age, with jaundice and hepatomegaly. Hepatitis proved to be autoimmune in nature and computerized tomography (CT) angiography confirmed SMA. The weight loss that preceded the SMA proved to be due to autoimmune thyroiditis and thyrotoxicosis. Duodenojejunostomy was not performed as she responded to carbimazole and nutritional support. Vomiting was controlled within a week. Hyperthyroidism can masquerade as SMA. Search for the underlying cause of weight loss leading to SMA is essential. We support the initial trial of conservative treatment for SMA.