Context: Patients previously treated with desiccated thyroid extract (DTE), when being switched to levothyroxine (L-T4), occasionally did not feel as well despite adequate dosing based on serum TSH levels.

Objective: Our objective was to investigate the effectiveness of DTE compared with L-T4 in hypothyroid patients.

Design and Setting: We conducted a randomized, double-blind, crossover study at a tertiary care center.

Patients: Patients (n = 70, age 1865 years) diagnosed with primary hypothyroidism on a stable dose of L-T4 for 6 months were included in the study.
Intervention: Patients were randomized to either DTE or L-T4 for 16 weeks and then crossed over for the same duration.

Outcome Measures: Biochemical and neurocognitive tests at baseline and at the end of each treatment period were evaluated.

Results: There were no differences in symptoms and neurocognitive measurements between the 2 therapies. Patients lost 3 lb on DTE treatment (172.9 36.4 lb vs 175.7 37.7 lb, P < .001).

At the end of the study, 34 patients (48.6%) preferred DTE, 13 (18.6%) preferred L-T4, and 23 (32.9%) had no preference. In the subgroup analyses, those patients who preferred DTE lost 4 lb during the DTE treatment, and their subjective symptoms were significantly better while taking DTE as measured by the general health questionnaire-12 and thyroid symptom questionnaire (P < .001 for both). Five variables were predictors of preference for DTE.

Conclusion: DTE therapy did not result in a significant improvement in quality of life; however, DTE caused modest weight loss and nearly half (48.6%) of the study patients expressed preference for DTE over L-T4. DTE therapy may be relevant for some hypothyroid patients.