Availability of Levothyroxine Formulations Impacts the Use of Thyroid Hormones: A THESIS Questionnaire Survey of Israeli Endocrinologists

Background:

Treatment of hypothyroidism is available in several formulations, including tablets, soft-gel capsules, liquid, as well as LT3 formulations.

Methods:

Israeli Endocrine Society (IES) members were invited to participate in the international incentive THESIS (Treatment of Hypothyroidism in Europe by Specialists: An International Survey).

Results:

A total of 123 physicians participated in the survey, with 65.1% women, 65.1% aged 41 to 60 years old, and 92.7% had more than 10 years in practice. LT4 tablets are used as first line therapy by 99.2% of respondents. Formulations prescribed include tablets by 100%, soft-gel capsules by 4%, liquid solution by 15.4%, compounded LT4 by 2.4%, and LT3 by 17.8%. In cases of impaired absorption (drugs or GI conditions) or inadequate control of hypothyroidism, most would continue LT4 tablets (86.1%-95.1%), of whom 36.6%-39% noted that only tablets are available in Israel. Only 4.9%-9% would prescribe other formulations. In comparison, in Italy were other formulations are readily available, soft-gel capsules would be prescribed by 29.7%-32% and liquid solution by 45.7%-66.9%. In patients with normal TSH and persistent symptoms, 95.1% would continue LT4 tablets (compared to 57.1% in Italy, 87.5% in Denmark, 75.4% in Romania). LT4/LT3 combination would be considered by 57.5%, whereas 24.4% stated this combination should never be used.

Conclusions:

In Israel, LT4 tablet formulation is the treatment of choice in most clinical scenarios, including in patients with impaired absorption or persistent symptoms. Other formulations, which are not widely available, are infrequently used compared with other European countries.