Primary hypothyroidism, affecting approximately 3% of the European population, has seen varied treatments over time. Early approaches involved administering thyroid extract through subcutaneous injections and oral routes. Until the 1970s, natural desiccated thyroid (NDT), derived from pig thyroid glands, was the predominant treatment for hypothyroidism globally. Since then, levothyroxine (L-thyroxine) has become the more common choice. However, there is growing evidence suggesting the effectiveness of liothyronine, found in NDT as a mixture with levothyroxine, for individuals who don't respond well to levothyroxine alone.
Historical Context of Thyroid Treatment
From the early 1890s to the mid-1970s, desiccated thyroid was the preferred treatment for hypothyroidism. In 1965, about 80% of thyroid hormone prescriptions in the USA were for natural thyroid preparations. Concerns about inconsistent potency arose when some tablets were found to have varying metabolic activity. While the standardization of iodine content to L-liothyronine (T3)/L-thyroxine (T4) content improved potency, the shift to levothyroxine was already underway in many countries.
What is NP Thyroid?
NP Thyroid is a type of natural desiccated thyroid (NDT) medication. Other similar preparations include NatureThroid and WP Thyroid. These medications contain a fixed ratio of levothyroxine and liothyronine, although the ratio can vary slightly between batches. There is also a bovine thyroid-derived NDT preparation available for individuals who cannot consume pork for religious or cultural reasons.
Usage and Prescription Trends
Over the past four decades, a small percentage of clinicians in the United Kingdom have prescribed NDT. Despite this, it remains available on the National Health Service (NHS) in England. In 2018/2019, 436 individuals in England received NDT prescriptions from their general practitioners (GPs). By 2022, this number decreased to an estimated 337 individuals. However, these figures do not include hospital or private prescriptions.
NICE Guidelines and Clinical Approaches
The UK National Institute for Health and Care Excellence (NICE) recommends further research on the clinical and cost-effectiveness of liothyronine/levothyroxine combination therapy compared to levothyroxine alone for those with persistent hypothyroid symptoms. In the absence of conclusive evidence, clinicians have adopted pragmatic approaches, with some prescribing NDT as a more affordable alternative to liothyronine.
Read also: Armour Thyroid: A Weight Loss Solution?
Cost and Prescription Analysis
In 2016, the average cost of NDT was £207 per prescription, which increased by 220% to £440 in 2022. Despite this increase, the cost remained below that of liothyronine. However, total annual prescriptions decreased by 44%, from 4,257 in 2016 to 2,384 in 2022.
Benefits Reported by NDT Users
Recent case series have indicated significant benefits for individuals treated with NDT due to their lack of response to levothyroxine. Patients reported alleviation of symptoms, suggesting the potential benefits of NDT. Some illustrative experiences include:
- Increased motivation and ease in getting up in the morning.
- Improved mental clarity and alertness.
- Better sleep quality.
- Increased energy levels.
- A return to feeling "normal" after years of discomfort.
- Significant improvements in energy levels, skin condition, and mental clarity.
- Reduction in anxiety and tension.
- Improved coping mechanisms and decision-making abilities.
- An overall improvement in the ability to participate in daily life.
Regulatory Status in North America
NDT was grandfathered in North America, meaning it did not undergo the standard licensing process. The Food and Drug Administration (FDA) allows some unapproved prescription drugs to be marketed if they meet the criteria of "generally recognized as safe and effective" (GRASE) or were grandfathered in before 1938. These drugs have not been formally approved by the FDA but were exempt from labeling or safety study changes under the Federal Food Drug and Cosmetics Act (FFDCA).
Cautions and Considerations
Current guidelines do not generally endorse the use of NDT, but many individuals worldwide report significant benefits from it. However, thyrotoxic symptoms and thyroid storm have been reported with inappropriate use of thyroid hormone extracts, including NDT. In the United Kingdom and Eire, NDT requires a prescription from a healthcare practitioner and is not available over the counter.
Emerging Evidence and Genetic Factors
Emerging evidence suggests that liothyronine's efficacy in NDT may benefit those unresponsive to levothyroxine. Free T3, the active thyroid hormone, is converted from Free T4 in tissues. Polymorphisms in the deiodinase-2 (DIO2) enzyme, present in 13% of the population, can reduce T3 levels in tissues like the brain without affecting serum levels.
Read also: Eating with Thyroid Nodules
Differing Opinions and Clinical Trials
Opinions remain divided on whether to pursue options other than levothyroxine for unresponsive individuals, with NDT being one such option. Two randomized double-blind controlled trials (RCTs) have compared NDT with levothyroxine. One RCT found that NDT therapy did not significantly improve quality of life but was associated with weight loss and a preference among nearly half the participants. Those who preferred NDT experienced weight loss and improved subjective symptoms.
Expert Opinions and Standardization Concerns
The American Thyroid Association concluded in 2014 that long-term outcome clinical trials are needed to test combination therapy or thyroid extracts. Some experts advise against using ArmourThyroid® due to perceived lack of standardization in liothyronine content. However, since 1985, the formulation of clinician-prescribed NDT has been considered reliable, contrary to some beliefs.
NDT as an Alternative Treatment
In countries where liothyronine prescriptions are costly, NDT may be a lower-cost alternative to combination treatment with levothyroxine and liothyronine. Some clinicians view NDT as beneficial for treating ongoing hypothyroid symptoms despite levothyroxine treatment. Studies have shown improvements in quality of life, as evidenced by changes in scores on the ThyPro and EQ5D5L scales.
Dosage and Administration
NDT therapy typically starts with low doses, gradually increasing based on the patient's cardiovascular status. A common starting dose is 30 mg of Armour Thyroid, with increments of 15 mg every 2 to 3 weeks. Patients with long-standing myxedema or suspected cardiovascular impairment should start with 15 mg/day. Angina symptoms indicate a need to reduce the dosage. Most patients require 60 to 120 mg/day, and failure to respond to 180 mg suggests non-compliance or malabsorption. Maintenance dosages of 60 to 120 mg/day usually result in normal serum T4 and T3 levels.
Patient Testimonials and Experiences
Many patients have shared their experiences with NDT, highlighting the positive impacts on their lives:
Read also: Myo-Inositol for Weight Loss
- Improved Energy and Mental Clarity: Patients report increased energy levels, better mental clarity, and an overall sense of well-being.
- Emotional and Psychological Benefits: Many users have experienced reduced depression and anxiety, improved mood, and a renewed interest in life.
- Physical Symptom Relief: Patients have noted improvements in symptoms such as dry skin, constipation, hair loss, and sensitivity to cold.
- Enhanced Quality of Life: Users describe a significant improvement in their ability to perform daily activities, engage in social interactions, and enjoy life.
- Weight Management: Some patients have experienced weight loss while taking NDT, although this is not a guaranteed outcome.
NP Thyroid vs. Synthroid
NP Thyroid and Synthroid are prescription medications used to treat hypothyroidism or thyroid cancer. NP Thyroid contains a mixture of T4 and T3 and is derived from pig thyroid glands, while Synthroid is a synthetic form of T4 (levothyroxine). Synthroid is FDA-approved, ensuring consistent manufacturing and hormone levels in each tablet. NP Thyroid, as a desiccated thyroid extract (DTE), does not have FDA approval and can vary in hormone levels between batches. Clinical guidelines generally prefer levothyroxine (Synthroid) alone for hypothyroidism treatment.
Cost and Availability
The cost of NP Thyroid can vary, with a typical out-of-pocket price around $60 for a one-month supply of 60 mg tablets. Brand-name Synthroid typically costs about $78 for 30, 50 mcg tablets.
Side Effects and Interactions
Side effects of both NP Thyroid and Synthroid are usually due to a dose that is too high, causing hyperthyroidism symptoms. It is important to inform your healthcare provider about all medications, including prescription drugs, over-the-counter medications, vitamins, and supplements. Certain foods and beverages, such as soybean flour, walnuts, dietary fiber, and grapefruit, may interact with the absorption of these medications.
Black Box Warning
Both NP Thyroid and Synthroid have a black box warning from the FDA stating that thyroid hormones should not be used for obesity treatment or weight loss, and higher doses can cause serious or life-threatening toxic effects.
Important Considerations
- Consultation with Healthcare Provider: It is crucial to consult with a healthcare provider before starting or changing thyroid medication.
- Regular Monitoring: Regular exams and blood tests are necessary to monitor the response to treatment.
- Adherence to Prescribed Dosage: Always take thyroid medication exactly as instructed by a healthcare professional.
- Awareness of Potential Interactions: Be aware of potential interactions with other medications and certain foods.