ODP445 If You Can't Beat Them, Join Them: A Therapeutic Strategy for Maintaining Euthyroidism in Non-Compliant Patients
Authors: Torres Angela Torres , Aviles Melendez Astrid M , Torres Yineli Ortiz , Osoria Gabriel Mora , Gonzalez Dainamar Perez , Cruz Alegyari Figueroa , Mateo Jose Garcia 
Published: November 2022

Levothyroxine (LT4) has been the mainstay therapy for hypothyroidism since synthesized in 1949, and it was depicted to be a daily, usually lifelong, therapy. LT4 may have many interactions with other medications, food, and supplements, for which it should also be taken on an empty stomach, at least thirty minutes before consuming any other product, to achieve adequate absorption. These two characteristics of LT4 therapy are two of the main reasons for patient non-compliance, leading to uncontrolled hypothyroid state shown by abnormal thyroid stimulating hormone (TSH) levels, and associated symptoms. LT4 properties, such as seven-day half-life, as well as increased peripheral conversion to metabolically active T3 by local deiodinase enzyme when there are low T4 levels, provide a scenario where it can be used at longer dosing intervals than the traditional daily dosing. This is the case of a 27-year-old female with past medical history of hypothyroidism on daily replacement therapy with 50mcg of branded LT4, presenting to the endocrinologist for continuation of care. Over the course of visits, patient showed uncontrolled thyroid disease with altered levels of TSH, ranging from 5.4 uIU/mL up to 46.8 uIU/mL (N: 0.45-5. 0 uIU/mL), despite appropriate dose adjustments and frequent TSH and free T4 (FT4) monitoring. Due to persistent clinical and biochemical hypothyroidism requiring dosage increases up to 300mcg, patient was referred for a thyroxine absorption test to rule out LT4 malabsorption versus medication non-compliance. A supervised dose of 812mcg of the same branded LT4 was provided, based on body weight, and TSH, free T3, and free T4 levels were measured before administration and sequentially at 30, 45, 60, 90, 120, 240, and 360 minutes after dose, yielding TSH values ranging from 0.11 uIU/mL to 0.18 uIU/mL, consistent with adequate TSH suppression. Patient admitted to erratic medication ingestion for which a dose of 150 mcg LT4 orally daily was started. TSH levels remained above 9. 0 uIU/mL, for which a trial of complete weekly dosage was offered and accepted by patient. Two months after therapeutic adjustment, patient became both clinically and biochemically euthyroid, with TSH level of 1.35 uIU/mL without any adverse effects from excess hormone intake. Medication non-compliance is an issue every physician must battle with. This case serves as an example of the great impact of individualized modification of LT4 administration to establish a therapeutic regimen that adjusts to each patient's lifestyle while allowing them to remain clinically stable, which is a great benefit for both the patient and the clinician. Although studies already exist in proving the benefits of weekly versus daily therapy in such patients without major risks, further investigation should be conducted, as therapeutic guidelines could potentially change altogether in the future to avoid, or at least reduce, non-compliance consequences.

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