Persistent Hypothyroidism Despite Levothyroxine Replacement Therapy: Malabsorption or Patient Noncompliance

Abstract

The most important reason for being unable to achieve euthyroidism in the treatment of hypothyroidism is noncompliance with treatment. The state of levothyroxine pseudomalabsorption is a factitious disorder where the patients present with noncompliance with l-thyroxine therapy. In order to diagnose levothyroxine pseudomalabsorption, an l-thyroxine absorption test may be performed. There are different protocols for the test, where 1000–2000 mcg l-thyroxine is given to the patient and blood is withdrawn at 2 h intervals, until up to 24 h. If the free thyroid hormone levels increase during the test, then this suggests that there is no malabsorption. The therapy of levothyroxine pseudomalabsorption may be parenteral infusion at the beginning to achieve an initial euthyroid state and giving the medication orally once or twice a day under medical supervision in the follow-up.