SLOT: Full Definition
What is WP Thyroid?
WP Thyroid is a brand of natural desiccated thyroid (NDT) manufactured by RLC Labs. Like other NDTs, it is derived from porcine (pig) thyroid glands and contains both T4 (thyroxine) and T3 (triiodothyronine) in a roughly 4:1 ratio. WP Thyroid is closely related to the historical product Nature-Throid, which was made by the same manufacturer; both have had supply interruptions and recalls in recent years.
WP Thyroid is prescribed for Hypothyroidism — including hypothyroidism due to Hashimotos Thyroiditis, thyroidectomy, or Radioactive Iodine Ablation — in patients who feel better on a combined T4/T3 medication than on T4 alone. Aliases include Nature-Throid (historical) and porcine thyroid extract.
How does WP Thyroid work?
A standard 65 mg (1 grain) tablet of WP Thyroid contains approximately 38 mcg of T4 plus 9 mcg of T3. The T4 portion gives a steady, slowly converted reservoir, while the T3 portion delivers immediate active hormone to the cells. Once T3 binds to thyroid hormone receptors, it activates the genes that regulate metabolism, body temperature, heart rate, cognition, mood, and menstrual cycles.
WP Thyroid was historically marketed for its minimal-filler formulation — fewer inactive ingredients than some other branded NDTs — which appeals to patients with sensitivities or autoimmune conditions. As with all NDT, monitoring requires a full panel including TSH, Free T4, and Free T3, alongside symptoms.
When is it prescribed?
WP Thyroid is typically considered when:
- A patient feels unwell on T4 alone despite an in-range TSH.
- Labs suggest poor T4-to-T3 conversion.
- A patient reacts to fillers in Armour Thyroid or Np Thyroid and prefers a minimal-excipient formulation.
- A patient prefers one combined tablet over separate T4 and Liothyronine.
Patient considerations
WP Thyroid is taken once daily — sometimes split — on an empty stomach, away from coffee, calcium, iron, magnesium, and biotin. Side effects reflect too much T3: palpitations, jitteriness, insomnia, anxiety, tremor, sweating, headaches, and unintended weight loss. Long-term over-replacement can contribute to bone loss and atrial fibrillation, especially in postmenopausal women. WP Thyroid is not appropriate for untreated adrenal insufficiency, uncorrected hyperthyroidism, or unstable cardiac disease, and pregnancy generally favors levothyroxine-based regimens.
WP Thyroid and Nature-Throid have had multiple recalls and supply interruptions in recent years. Many patients were forced to switch to Armour, NP Thyroid, or Compounded T3 T4 during shortages, and some never returned even after WP Thyroid became available again. Because it is pork-derived, WP Thyroid is unsuitable for vegetarians, vegans, and patients with religious restrictions.
At Modern Thyroid Clinic, WP Thyroid is one of several NDT options. The right medication is the one that produces stable labs, steady energy, clear thinking, and a body that feels like itself again.
Common symptoms
Common questions
What's the difference between WP Thyroid and Nature-Throid?
WP Thyroid and Nature-Throid were both made by RLC Labs and contain a similar T4-to-T3 profile from porcine glands. WP Thyroid was originally marketed as a cleaner formulation with fewer fillers, while Nature-Throid had a slightly different excipient list. Both products experienced recalls and supply disruptions; Nature-Throid was discontinued at one point. If you were on Nature-Throid historically, your clinician may have moved you to WP Thyroid, Armour, NP Thyroid, or compounded NDT depending on availability.
Is WP Thyroid hypoallergenic?
WP Thyroid was historically marketed for its minimal-excipient formulation — fewer dyes, binders, and fillers than some other thyroid medications — which is helpful for patients with food sensitivities, gluten reactions, or autoimmune conditions like Hashimoto's. "Hypoallergenic" is not an FDA term, though, and the product still contains pork-derived thyroid tissue and some inactive ingredients. Patients with confirmed allergies should always review the current ingredient list with their pharmacist.
Why has WP Thyroid been hard to find?
RLC Labs, the manufacturer of WP Thyroid and Nature-Throid, has had multiple recalls, manufacturing interruptions, and supply shortages over the past several years. These have forced many patients to temporarily or permanently switch to Armour Thyroid, NP Thyroid, or compounded NDT. If your pharmacy cannot fill WP Thyroid, your clinician can usually transition you to a comparable medication and confirm dosing with a six-week lab recheck rather than leaving you without thyroid hormone.
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Book a Discovery CallThis content is for educational purposes only and is not medical advice. Consult a licensed clinician for diagnosis and treatment. Content on this page does not create a doctor-patient relationship with Modern Thyroid Clinic.