SAT-352 - Gut Check: Resolving Refractory Hypothyroidism Through H. Pylori Eradication

Case Presentation:
A 37-year-old male with Trisomy 21, celiac disease (diagnosed in adolescence), and hypothyroidism secondary to Hashimoto’s thyroiditis presented to endocrinology clinic with persistent hypothyroidism despite escalating doses of levothyroxine and recent weight loss. He currently weighs 46 kg with a body mass index of 24.4. Notably, he resides in a supervised care facility and is adherent to all medication, adherent to a strict gluten-free diet, and waits 1-2 hours after taking levothyroxine before eating, per facility staff. Laboratory studies were notable for TSH of 112 uIU/mL (0.450 - 5.330 uIU/mL) despite being on levothyroxine 225 mcg daily, much exceeding predicted weight-based dose of approximately 75 mcg daily (1.6 x 46 kg). Liquid levothyroxine was tried in the past with no improvement in elevated TSH. Given the significant discordance between expected and actual dosing of levothyroxine in combination with weight loss, the patient was referred to gastroenterology for malabsorption workup.

Initial GI evaluation revealed normal B12, CBC, iron panel, and negative celiac serologies (TTG, IgA) indicating well-controlled celiac disease. Upper endoscopy was then performed given continued weight loss in setting of refractory hypothyroidism; findings were consistent with chronic active Helicobacter pylori gastritis. The patient was treated with clarithromycin 500 mg oral twice daily, lansoprazole 30 mg oral BID, and metronidazole 500 mg twice daily. Eradication was confirmed 6 weeks later. Following H. pylori treatment, thyroid function tests were monitored closely every 2-3 months, showing low TSH, and his dose was decreased multiple times over the subsequent months. He has now achieved sustained biochemical euthyroidism on levothyroxine 75 mcg daily, matching expected weight-based dosing.

Clinical Significance:
This case advocates for consideration of active H. pylori in patients presenting with refractory hypothyroidism. Additionally, refractory hypothyroidism may be considered a “red flag” for malabsorption, especially in underweight individuals. This case was complicated by pre-existing celiac disease, potentially leading to bias when considering etiologies of his malabsorption. This case also demonstrates the risk of transient thyrotoxicosis post-H. Pylori eradication, highlighted by the dramatic levothyroxine dose reduction (from 225 mcg daily to 75 mcg daily) after treatment, and need for close TSH monitoring. Multi-disciplinary care (primary care, endocrine, and gastroenterology) was crucial to this patient’s positive outcome.

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