Pseudomalabsorção de levotiroxina: relato de um caso

Abstract

A 49-year-old woman who had been treated with sodium levothyroxine because of hypothyroidism after diagnosis of Hashimoto thyroiditis and total thyroidectomy for multinodular atoxic goiter was evaluated for persistent hypothyroidism despite the use of large doses of levothyroxine (600 microg/day). The patient showed signs and symptoms of hypothyroidism and her laboratory tests were: TSH of 351 microUI/mL, free thyroxine of 0.20 ng/dL, and total triiodothyronine of 27 ng/dL. She was submitted, under medical supervision, to a levothyroxine overload test with no evidence of malabsorption of the thyroid hormone. Diagnosis of factitious disorder and Munchausen syndrome leading to the pseudomalabsorption of levothyroxine was considered.

Validity of the Rapid Thyroxine Absorption Test for the Differentiation Between Levothyroxine Non-compliance and Malabsorption in Thyroid-Stimulating Hormone Refractory Hypothyroidism

“…Poor adherence to daily administration of LT4 is the most common cause for non-responding to high doses of LT4 [21]. The LT4 absorption tests (different protocols) are used to differentiate between non-compliance and true malabsorption [17,18]. In the current study, we consider the long-supervised LT4 absorption test as a gold standard test for comparison with and validity assessment of other tests for multiple reasons.…”

“…Even after careful consideration of all factors that lead to malabsorption, still there are difficulties to differentiate malabsorption from non-compliance. A large single dose and a weekly dose of LT4 are two protocols used to discriminate malabsorption from non-compliance in TSH refractory hypothyroidism [17,18].…”

Increased levothyroxine requirement in a woman with previously well-controlled hypothyroidism and intestinal giardiasis

“…Routinely ordered tests include: anti--gliadin antibodies (for celiac disease), inflammation markers (for inflammatory intestinal disease), lactose tolerance test (for lactose intolerance) (6,7), and, occasionally, anti-T4 antibodies (8). Short bowel syndrome after intestinal or bariatric surgery, hepatic cirrhosis and congestive heart failure can also impair L-T4 intestinal absorption, and should be investigated if there is clinical suspicion (3,6).…”