A Tale of Two Therapies- A Comparison of Armour Thyroid and Levothyroxine

Treatment of hypothyroidism is predominantly with levothyroxine due to its ability to generate stable T3 levels and its long half-life. Many patients report continued hypothyroid symptoms despite normal TSH values on levothyroxine and request to switch to desiccated animal thyroid extract. Desiccated thyroid extract is less used for fear of side effects and risks. There are only a handful of studies available comparing desiccated animal thyroid extract to levothyroxine. We conducted a retrospective study on 250 hypothyroid patients over the age of 18 who presented to our clinic from 2008-2018. We excluded patients who had a history of thyroid cancer and documented non-adherence. We analyzed 125 patients on levothyroxine (males=43, females=82) and 125 patients who were on levothyroxine but chose to switch to Armour Thyroid (males=7, females=118). We examined the following variables; when comparisons of proportions were made between the two groups, N-1 chi square test was used to determine significance. 1. Reason for change to Armour Thyroid from levothyroxine: Top reasons were fatigue (n=51/125, 40.8%), inability to lose weight (n=32/125, 25.6%), mental fog (n=8/125, 6.4%), hair loss (n=8/125, 6.4%) and desire for a natural product (n=7/125, 5.6%) 2. Percentage of patients complaining of fatigue/weight gain in euthyroid state: 16/125 (12.8%) of patients on Armour Thyroid and 29/125 (23.2%) of patients on levothyroxine had complaints of fatigue and weight gain with a normal TSH. This 10.4% difference was significant (p value=0.033, 95% CI 0.84% to 19.8%). 3. Presence of side effects: 24/125 (19.2%) patients on Armour Thyroid discontinued it before 6 months. The top reasons were no improvement of symptoms (n=9/24, 37.5%), palpitations (n=5/24, 20.8%), worsening anxiety (n=3/24, 12.5%), cost (n=2/24, 8.33%), and loss of appetite (n=2/24, 8.33%). 5/125 (4.00%) patients on levothyroxine chose to discontinue it before 6 months. The reasons included presence of palpitations (n=3/5, 60.0%), hair loss (n=1/5, 20.0%), and gluten intolerance (n=1/5, 20.0%). A total of 11/125 (8.8%) had adverse effects from Armour Thyroid while 4/125 (3.2%) of patients on levothyroxine had adverse effects to the medication. The difference of 5.6% leaned toward clinical significance and trended toward being statistically significant (p value=0.06, CI -0.4842% to 12.1677%). Our research shows that patients generally feel better on Armour Thyroid compared to levothyroxine. Armour Thyroid is an effective medication to use for patients who remain symptomatic on levothyroxine and should be considered as a viable option in clinical practice. However, our study also indicated that patients may have more adverse effects on Armour Thyroid when compared to levothyroxine and further studies are needed comparing the two medications. Limitations of our study include the retrospective nature of the study and the sample size.