T4 / NDT (levothyroxine, desiccated thyroid)
Hormones · Thyroid hormone replacement
Tier B-
What this is
Guidelines favor T4 monotherapy but NDT enjoys a dedicated following. Resistance to change may reflect imperfect T4→T3 deiodinase activity in subsets of patients (DIO2 polymorphism work). Generic levothyroxine is bioequivalent per FDA but brand consistency sometimes matters clinically. Take on empty stomach 30-60 min before food/supplements.
Mechanism
T4 = prohormone converted to T3 peripherally via deiodinases; standard hypothyroid therapy; NDT (Armour, NP Thyroid) provides porcine-derived T4+T3 in ~4:1 ratio
Dose & route
T4: 1.6 mcg/kg/day; NDT: 1 grain (60 mg) starting, titrate to TSH/symptoms
Citations
- https://pubmed.ncbi.nlm.nih.gov/25266247/
- https://pubmed.ncbi.nlm.nih.gov/19011087/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC5785757/
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This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.