Desiccated Thyroid (NDT): What You Need to Know

If you’re curious about desiccated thyroid—often called NDT or natural desiccated thyroid—here’s a direct, practical rundown. NDT is made from porcine thyroid glands and contains a mix of T4 and T3 hormones, not just levothyroxine (T4) alone. Some people feel better on NDT because it provides both hormones, but that doesn’t make it right for everyone.

How NDT works and who might try it

NDT supplies T4 and T3 together. T4 converts to T3 in the body, but some people don’t convert well and report lingering symptoms on levothyroxine alone—fatigue, brain fog, or stubborn weight gain. That’s when some patients and clinicians consider NDT. If you have a healthy heart and no serious medical issues, a trial of NDT under medical supervision can be reasonable.

Quick practical point: many clinicians use a conversion rule when switching from levothyroxine to NDT. Roughly 1 grain of NDT (about 60–65 mg) is often considered equivalent to about 100 mcg of levothyroxine. That’s a starting guideline—not a prescription. Doses need adjustment by your clinician and lab results.

Safety, monitoring, and everyday tips

Because NDT contains T3, it can cause quicker changes in heart rate and energy. Watch for palpitations, anxiety, heat intolerance, or trouble sleeping. Older adults or people with heart disease should start very low and be followed closely.

Lab checks matter: get TSH, free T4 and free T3 tested about 6–8 weeks after any dose change. Keep the same brand if possible—NDT brands vary and swapping brands can change your hormone levels. Take NDT on an empty stomach and avoid calcium or iron supplements within four hours of your dose; those minerals cut absorption.

Pregnancy and breastfeeding usually favor levothyroxine because it’s easier to dose precisely. If you’re pregnant or planning pregnancy, talk to your clinician before switching.

If you consider buying thyroid meds online, be careful. Work with your prescriber, verify the pharmacy, and confirm the product is legitimate. Our site has an article about monitoring levothyroxine levels that’s useful if you want to understand lab follow-up and dose checks.

Bottom line: NDT can help the right person, but it needs thoughtful prescribing and follow-up. Talk openly with your clinician about symptoms, labs, heart risks, and whether a trial of NDT makes sense for your situation.