Endocrine Abstracts

Introduction: Hypothyroidism is a common endocrine disease with reduced systemic metabolism and its treatment consists on hormonal supplementation. However, despite concurrent replacement therapy with high doses of L-thyroxin, some patients might be seen with clinical and biochemical evidence of hypothyroidism. We report a case of persistent hypothyroidism on high dose of levothyroxin.

Case presentation: It was a 41-year-old female, with a history of recurrent chronic Helicobacter pylori gastritis and total thyroidectomy for a multinodular goitre in 2017, treated with 900 μg per day of L-thyroxin with good compliance and regular intake. She was admitted in our department in December 2021 for exploration. Clinically, she had signs of hypothyroidism: asthenia, puffy face, pudgy fingers and macroglossia. Biology revealed a TSH= 55.32 μUI/ml and a FT4 < 0.42 ng/dl. A levothyroxin absorption test under medical supervision was performed with 600μg of L-thyroxin. TSH and FT4 were measured before the test and at 2h, 4h, 6h and 24h after the test. The FT4 remained low with a peak at 0.48 ng/dl (2h after the start of the test). The test concluded that there was malabsorption of thyroid hormones. Serological markers for celiac disease and a new digestive fibroscopy were requested.

Conclusion: This case illustrates the interest of the thyroid hormone test which allows to distinguish between malabsorption and pseudomalabsorption, non compliance to the treatment. If the diagnosis of malabsorption is retained, further investigations for etiological purposes should be carried out.