DTE is naturally derived from animal extracts and is standardized in different ways; it generally contains T3 and T4 in a 1:4 ratio and is made in a range of strengths. Because these preparations contain variable quantities of T3, they should not be prescribed for patients with known or suspected cardiac disease or in pregnancy.
Although DTE remained the cornerstone of hypothyroidism treatment for decades, treatment response was inconsistent and unpredictable, with reports of either continued hypothyroidism or iatrogenic thyrotoxicosis. With increasing use of the TSH radioimmunoassay as a treatment follow-up tool and the discovery of conversion of T4 to T3 in humans, clinical practice transitioned toward the adoption of levothyroxine as the standard of care for the treatment of hypothyroidism. Since then, levothyroxine monotherapy has been considered to have a favorable safety profile and greater effectiveness in normalizing the serum TSH level, the most sensitive marker of hypothyroidism-treatment response.
Research has found no differences in symptoms and neurocognitive measurements between therapies, but some difference in weight loss, after DTE treatment compared with levothyroxine-based therapy. And although some patients report more favorable quality-of-life responses to DTE, many also report highly variable treatment responses, adverse events, new or unexpected symptoms, TSH changes, or even thyrotoxicosis, and a general inability to titrate DTE doses reliably.
Learn more about hypothyroid medications.
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Cite this: Mary L. Windle. Rapid Rx Quiz: Thyroid Drugs - Medscape - Jul 20, 2022.