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AUSTIN -- Among patients with hypothyroidism, a once weekly dose of L-thyroxine was an acceptable treatment alternative to daily dosing, researchers reported here.

Led by Satish Wasoori, MD, of Park Hospital in India, and colleagues, the prospective observational study found euthyroidism was achievable with once weekly L-thyroxine among previously non-compliant young and middle-aged adults.

Presented at the American Association of Clinical Endocrinologists' annual meeting, the study showed similar outcomes even among patients recently diagnosed with hypothyroidism.

The authors highlighted current guidelines for treatment of adults with hypothyroidism stating that daily L-thyroxine is "an appropriate gold standard therapy." A typical daily dose is 1.6 to 1.8 mcg/kg/day.

Wasoori's group randomized 180 patients, ranging from 18 to 55 years of age, into three study groups, all with an established diagnosis of hypothyroidism. All participants were screened for malabsorption prior to study inception, and none were reportedly receiving any drugs that would inhibit L-thyroxine absorption.

The first study group, which included 60 subjects, were administered a once-weekly dose of L-thyroxine, seven times the typical daily dose. These individuals, which were on daily L-thyroxine prior to intervention, also had baseline TSH values of 4.2 or less.

Sixty participants were included in the second study group, who were administered a weekly dose seven-fold that of a normal daily dose, yet the dose was more individualized, specifically for dosing in terms of body weight and TSH value. All participants in this group had TSH values over 4.2, and were also previously on daily dosing.

The third group, which included 60 newly diagnosed patients who were not on treatment yet, was provided a weekly dose of L-thyroxine specifically measured for individualized body weight and TSH levels, all of which were over 4.2.

The lowest weekly dose of L-thyroxine reported during the study was 175 mcg, while the maximum was 1,050 mcg.

Across all study groups, the majority of participants were able to achieve complete restoration of euthyroidism with once-weekly L-thyroxine. All but one patient (n=59) in the first study group were able to achieve euthyroidism by 12 weeks, continued through 24 weeks. Only one participant was withdrawn from this group, due to hyperthyroid symptoms.

A total of 52 participants in the second study group achieved euthyroidism by 12 weeks. By 24 weeks, five remaining participants still had not achieved normal thyroid function. Wasoori's group noted that this may be due to external metabolic disorders, such as obesity or diabetes.

By 12 weeks in the third group, 54 participants had normal thyroid function, with 59 reaching euthyroidism by 24 weeks. The researchers noted that the last patient in this group relocated and did not finish the trial.

Wasoori's group stated that these findings suggest higher weekly treatment dosage may be a "valid therapeutic option and can also be considered as a first line therapy," particularly among those who are non-adherent to daily dosing. They added this may be particularly suitable to working-age adults who may experience impaired absorption due to mealtimes.

Significant differences were also reported for LDL and triglyceride levels among groups 2 and 3. However, the authors added that some literature has linked higher FT4 levels with increased risk of sudden cardiac death, and recommend future studies on one-weekly dosing measure cardiac safety.

"If we did the same experiment with Cytomel [liothyronine sodium], or T3, it would be very dangerous," added S. Sethu Reddy, MD, chair of the AACE annual program committee and the moderator of the oral session, highlighting that the method of absorption of this treatment was vital.

Click for AACE's clinical practice guidelines for the treatment of adults with hypothyroidism.

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