Endocrine Abstracts

Background: levothyroxine is the most common medication for the treatment of hypothyroidism. Usually, it is capable of restoring euthyroidism in most conditions. Absorption can be challenging, therefore different formulations are available (tablet, soft gel, liquid). Rarely it is necessary to use liothyronine to achieve normal TSH values.

Clinical case: a 23 y/o woman was admitted to our outpatient clinic for severe hypothyroidism. She was diagnosed with autoimmune thyroiditis at the age of 10. She also has celiac disease and schizoaffective disorder. She lived in a community and was followed by medical personnel. She was on a gluten-free diet and antipsychotic drugs: Lithium, Duloxetine, Lorazepam, Clozapine and quetiapine. On medical examination, she has obesity with no cushingoid aspect, normal heartbeat and blood pressure. She felt tired and had regular menses. She denied any other specific symptoms. She was on treatment with Levothyroxine tabs 200 mg/day (1.78 mg/kg/day), and her TSH was 386 mU/l with no measurable Ft3 and FT4. We excluded Helicobacter pylori infection and emphasized the need for a gluten-free diet and the correct way of taking medication. We advised a shift to soft gel formulation increasing the dose up to 250 mg/day After two months her TSH was 18.1 mU/l. Four months later her TSH was 1 mU/l, we therefore gradually increased levothyroxine to 1 mg shifting to liquid formulation with no benefit. We then changed the levothyroxine brand. We gradually added liothyronine up to 15 mg 3 times per day. After 2 months she was on levothyroxine 1 mg (3 mg/kg/day) and liothyronine 1 mg per day and her TSH was 1 mU/l. We investigated with caregivers who assured us she took medication correctly and properly followed the diet. She could have severe malabsorption so we undertook the levothyroxine absorption test. While she was having the test we realized that she couldn’t empty the bottle. We then explained to her and her caregiver how to take the medication and she restored euthyroidism with levothyroxine 164 mg/day (1.6 mg/kg/day) without the need for liothyronine. Regardless of thyroid hormone values she never complained of any other symptoms, or benefit from the restored euthyroidism.

Conclusion: psychiatric patients can be challenging and symptoms can be underestimated. The new formulation of levothyroxine allows us to tailor approaches. Using the right medication and the right formulation for the right patient is crucial. Levothyroxine absorption test can still be used in specific settings.