Mahmoud Nassar, Ahmed Hassan, Shrouk Ramadan, Mariam Tarek Desouki, Malak A Hassan, Ajay Chaudhuri
Journal: BMC endocrine disorders 2024;24(1):90
PMID: 38877429
Hypothyroidism is a condition where the thyroid gland is unable to produce enough hormones to maintain the body’s ability to convert food into energy. As a result, individuals can experience symptoms such as fatigue and weight gain. The first line treatment is a synthetic form of thyroid hormone called levothyroxine (LT4). However, there are still some individuals in whom this therapy has no effect. As a result combination therapies are being considered and the use of desiccated thyroid extract (DTE), which derives from animal thyroid glands. This systematic review and meta-analysis of 16 studies aimed to determine the effect of DTE and a combination of the thyroid hormones thyroxine (T4) with triiodothyronine (T3) on individuals with hypothyroidism. The results showed that compared to T4 alone, combined T4+T3 and DTE resulted in more favourable hormone levels. However, this did not affect hormones that stimulate thyroid hormone production, heart rate, blood sugar levels, blood lipid levels or quality of life. It was concluded that combined T4+T3 and DTE result in altered thyroid hormone levels compared to T4 alone, however it is unclear if this has any clinical benefit. This study could be used by healthcare professionals to understand that there may be alternative therapies for balancing thyroid hormones in individuals with hypothyroidism. However, individuals may still experience clinical symptoms and it is questionable whether this course of treatment is of use.
BACKGROUND
Persistent symptoms in hypothyroid patients despite normalized TSH levels suggest the need for alternative treatments. This study aims to evaluate the effectiveness of combined T4 and T3 therapy or desiccated thyroid (DTE) compared to T4 monotherapy, with a focus on thyroid profile, lipid profile, and quality of life metrics.
METHODS
We conducted a systematic review in Embase, Medline/PubMed, and Web of Science up to 11/23/2023. We used the following keywords: "Armour Thyroid," OR "Thyroid extract," OR "Natural desiccated thyroid," OR "Nature-Throid," "desiccated thyroid," OR "np thyroid," OR "Synthroid," OR "levothyroxine," OR "Liothyronine," "Cytomel," OR "Thyroid USP," OR "Unithroid." AND "hypothyroidism. " We only included RCTs and excluded non-RCT, case-control studies, and non-English articles.
RESULTS
From 6,394 identified records, 16 studies qualified after screening and eligibility checks. We included two studies on desiccated thyroid and 15 studies on combined therapy. In this meta-analysis, combination therapy with T4 + T3 revealed significantly lower Free T4 levels (mean difference (MD): -0.34; 95% CI: -0.47, -0.20), Total T4 levels (mean difference: -2.20; 95% CI: -3.03, -1.37), and GHQ-28 scores (MD: -2.89; 95% CI: -3.16, -2.63), compared to T4 monotherapy. Total T3 levels were significantly higher in combined therapy (MD: 29.82; 95% CI: 22.40, 37.25). The analyses demonstrated moderate to high heterogeneity. There was no significant difference in Heart Rate, SHBG, TSH, Lipid profile, TSQ-36, and BDI Score. Subjects on DTE had significantly higher serum Total T3 levels (MD: 50.90; 95% CI: 42.39, 59.42) and significantly lower serum Total T4 (MD: -3.11; 95% CI: -3.64, -2.58) and Free T4 levels (MD: -0.50; 95% CI: -0.57, -0.43) compared to T4 monotherapy. Moreover, DTE treatment showed modestly higher TSH levels (MD: 0.49; 95% CI: 0.17, 0.80). The analyses indicated low heterogeneity. There was no significant difference in Heart Rate, SHBG, Lipid profile, TSQ-36, GHQ-28, and BDI Score.
CONCLUSIONS
Our study revealed that combined therapy and DTE lead to higher T3 and lower T4 levels, compared to T4 monotherapy in hypothyroidism. However, no significant effects on heart rate, lipid profile, or quality of life were noted. Given the heterogeneity of results, personalized treatment approaches are recommended.
© 2024. The Author(s).
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