Endocrine Abstracts

Introduction: Non-celiac gluten sensitivity (NCGS) belongs to gluten-related disorders. Patients with NCGS develop a variety of intestinal and/or extraintestinal symptoms such as abdominal pain, bloating, bowel habit abnormalities, nausea, gastroesophageal reflux disease and aphthous stomatitis, that improve when gluten is removed from the diet. The diagnosis is made after exclusion of coeliac disease and wheat allergy. Although thyroxine malabsorption has been described in patients with coeliac disease, data on thyroxine absorption in patients with NCGS is lacking so far.

Case-report: A 41-year-old female, with a history of thyroidectomy 2 years ago, presented at the outpatient clinic with chronic hypothyroidism despite progressively increasing doses of levothyroxine (400 μg oral L-thyroxine tablets, plus 100 μg triiodothyronine tablets daily). She stated that she had been experiencing persistent tiredness, general weakness, menorrhagia and severe anemia due to iron deficiency. She had also been suffering from abdominal pain and bloating, and was diagnosed with reflux esophagitis a year ago. Clinical evaluation confirmed severe hypothyroidism with periorbital edema, swelling of the face and lips, dry skin, muscle weakness and bradycardia. Laboratory tests revealed elevated TSH levels (72, 2 mlU/l) with remarkably low FT3 (<0, 1 ng/dl) and FT4 (<0.42 ng/dl). The patient did not tolerate iv thyroxine; thus she switched on 150 μg/d oral L-thyroxine in liquid form, which was increased progressively to 200 μg/d. Laboratory workup for a possible malabsorptive etiology was negative for coeliac disease or intrinsic anemia as tissue transglutaminase antibodies type IgG and IgA, anti-gliadin IgG antibodies, anti-endomysial antibodies and antiparietal cell antibodies were undetectable. Additionally, endoscopic control revealed the histological picture of mild esophagitis and chronic duodenitis with lymph follicle hyperplasia. However no mucosal changes typical for coeliac disease were identified. The patient was started on pantoprazole 40 mg once daily but 2 months later gastroenteric symptoms persisted and TSH level was still elevated to 25 mlU/l. NCGS was suspected and the patient was advised to follow a gluten-free diet. Subsequently she had normal thyroid function values, with remarkable improvement of her clinical symptoms. Currently, she is on treatment with 200 μg/d oral L-thyroxine in liquid form and remains euthyroid with normal hematological and biochemical laboratory tests.

Conclusion: Data on thyroxine malabsorption associated with NCGS are scarce. Our case highlights that unknown mechanisms associated with gluten sensitivity may be involved in the malabsorption of oral L-thyroxine in solid tablets format. An empirical switch to liquid formulation concomitantly with a free-gluten diet may resolve this therapy refractory issue.