From the Guidelines
Synthroid and NP Thyroid are both effective treatments for hypothyroidism, but the choice between them should be individualized based on patient response, conversion ability, and preference, always under medical supervision. Synthroid (levothyroxine) is a synthetic form of the T4 thyroid hormone only, while NP Thyroid is a natural desiccated thyroid product derived from pig thyroid glands containing both T4 and T3 hormones. This fundamental difference affects how they work in the body. Synthroid provides only T4, which your body must convert to the active T3 hormone, making it a more predictable option with consistent potency between batches 1. NP Thyroid delivers both hormones directly, potentially beneficial for patients who have difficulty converting T4 to T3.
Some key points to consider when choosing between Synthroid and NP Thyroid include:
- Dosing: Synthroid is typically taken once daily on an empty stomach, while NP Thyroid may require multiple daily doses.
- Side effect profiles: Some patients may experience better symptom relief with one versus the other, and careful monitoring is necessary to minimize adverse effects 1.
- Conversion ability: Patients who have difficulty converting T4 to T3 may benefit from NP Thyroid, which delivers both hormones directly.
- Patient preference: The choice between Synthroid and NP Thyroid should be individualized based on patient preference, always under medical supervision 1.
It's also important to note that overdiagnosis and overtreatment of thyroid dysfunction are concerns, and careful consideration should be given to the potential harms of treatment, including the risk of osteoporosis, fractures, and abnormal cardiac output 1. Ultimately, the decision between Synthroid and NP Thyroid should be made on a case-by-case basis, taking into account the individual patient's needs and circumstances.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Difference between Synthroid and NP Thyroid
- Synthroid is a synthetic form of levothyroxine (T4), a hormone that is produced naturally by the thyroid gland 2, 3.
- NP Thyroid is a natural desiccated thyroid (NDT) product that contains both T4 and triiodothyronine (T3), as well as other thyroid hormones 4, 5.
- The main difference between Synthroid and NP Thyroid is the type of thyroid hormones they contain, with Synthroid containing only T4 and NP Thyroid containing a combination of T4 and T3 2, 3.
- Some studies suggest that combination therapy with T4 and T3 may be beneficial for some patients with hypothyroidism, particularly those who remain symptomatic despite adequate T4 monotherapy 3, 4, 5.
Mechanism of Action
- T4 is converted to T3 in the body, which is the more active form of the hormone 2, 3.
- T3 plays a crucial role in regulating metabolism, energy production, and other bodily functions 3, 5.
- The combination of T4 and T3 in NP Thyroid may provide a more physiological replacement of thyroid hormones, which may be beneficial for some patients 4, 5.
Clinical Use
- Synthroid is commonly used as a first-line treatment for hypothyroidism, and is often effective in managing symptoms and normalizing thyroid function tests 2, 3.
- NP Thyroid may be considered for patients who remain symptomatic despite adequate T4 monotherapy, or for those who prefer a more natural form of thyroid hormone replacement 4, 5.
- However, the use of NP Thyroid should be carefully monitored, as it can be associated with adverse effects, particularly if the dose is too high 4, 6.