Resistance to Thyroid Hormone in Crohn's Disease: A Clinical Challenge of Refractory Thyroid Stimulating Hormone Elevation and Therapeutic Dilemmas

Thyroid hormone resistance (RTH) is a rare genetic disorder characterized by diminished responsiveness of target tissues to thyroid hormones, primarily due to mutations in the thyroid hormone receptor-beta (TR-β) gene. This condition could lead to an increased level of Thyroid stimulating hormone (TSH) and varying degrees of hypothyroid symptoms, despite normal or elevated levels of circulating thyroid hormones. Concurrently, Crohn's disease (CD), an inflammatory bowel disease, poses significant diagnostic and therapeutic challenges due to its multifactorial etiology and association with various autoimmune disorders. This case report describes a 30-year-old female patient diagnosed with both RTH and CD. Given a history of thyroidectomy, the patient was on Levothyroxine supplement and also was taking corticosteroids for Crohn's disease. Despite adherence to therapy, persistently elevated TSH levels were noted, and the patient still exhibited signs of hypothyroidism. Altogether, it raised suspicions for RTH. After 1 year, we successfully managed her Crohn's disease, achieving sustained remission. Surprisingly, clinical and biochemical markers of hypothyroidism also showed significant improvement. This case illustrates the intricate relationship between autoimmune conditions and thyroid dysfunction, emphasizing the necessity for comprehensive evaluation in patients with overlapping symptoms. The findings highlight the importance of recognizing RTH in patients with unexplained thyroid abnormalities, particularly in the context of coexisting inflammatory bowel diseases, to optimize management and improve patient outcomes.