One Grain of NP Thyroid Equals 60 Milligrams
One grain of NP Thyroid contains 60 mg of desiccated thyroid extract 1.
Standardized Dosing Information
The FDA-approved NP Thyroid product labeling clearly specifies the grain-to-milligram conversion across all available tablet strengths 1:
- 1/4 grain = 15 mg
- 1/2 grain = 30 mg
- 1 grain = 60 mg
- 1 1/2 grain = 90 mg
- 2 grain = 120 mg
Thyroid Hormone Content Per Grain
Each grain (60 mg) of NP Thyroid provides a standardized amount of thyroid hormones 1:
- 38 mcg of levothyroxine (T4)
- 9 mcg of liothyronine (T3)
This creates an approximate T4:T3 ratio of 4:1 by weight, which is consistent across desiccated thyroid preparations of porcine origin 2.
Important Clinical Considerations
The grain measurement is an outdated apothecary unit that persists in thyroid medication nomenclature. While manufacturers continue to label products using grains for historical continuity, prescribers should use milligram dosing for precision and clarity.
Key Caveats:
- The T4:T3 ratio in desiccated thyroid differs substantially from human thyroid physiology and synthetic levothyroxine monotherapy
- Desiccated thyroid preparations have not been systematically studied compared to levothyroxine 2
- The content and ratio of thyroid hormones may vary between different brands of desiccated thyroid 2