NP Thyroid Composition
NP Thyroid is a natural desiccated thyroid extract (DTE) derived from porcine (pig) thyroid glands that contains both thyroxine (T4) and triiodothyronine (T3) in a ratio of approximately 4:1. 1, 2
Active Hormonal Components
DTE contains both T4 and T3 thyroid hormones extracted from animal thyroid tissue, distinguishing it from synthetic levothyroxine which contains only T4. 3, 4
The T4 to T3 ratio in desiccated thyroid preparations is approximately 4:1, meaning patients receive roughly 11 mcg of T3 per typical daily dose needed to normalize TSH, though some patients may require higher doses. 1
Both hormones are naturally present in the thyroid gland tissue rather than being synthetically combined, as the extraction process preserves the hormonal content of the source gland. 2
Historical Context and Current Status
Natural thyroid preparations including desiccated thyroid dominated the pharmaceutical market for most of the 20th century before synthetic levothyroxine became the standard of care in the 1970s. 2
DTE remains outside formal FDA oversight, with consistency of T4 and T3 contents monitored only by manufacturers rather than through rigorous regulatory processes. 1
Clinical Considerations
The absorption of T3 from DTE can cause serum T3 levels to rise to supranormal values during the absorption phase, which has been associated with palpitations and represents a key concern with this formulation. 3, 4
Concerns about inconsistencies in desiccated thyroid preparations were one of the factors that led to the transition toward synthetic levothyroxine monotherapy as the preferred treatment. 2