Desiccated Thyroid (Thyroid USP)
Desiccated thyroid extract is dried porcine (or bovine) thyroid gland standardised to thyroid hormone content, containing both T4 and T3. Marketed as Armour Thyroid and others for hypothyroidism, it is used off-label as a natural-source thyroid aid for cutting.
01 Overview
Desiccated thyroid is one of the oldest thyroid replacements, predating synthetic hormones. Each grain (~65 mg) supplies roughly 38 mcg T4 and 9 mcg T3 plus other iodothyronines, giving a combined hormone profile some users prefer to levothyroxine alone.
In physique use it is taken supraphysiologically to raise metabolic rate. Because T3:T4 ratios in animal glands differ from human physiology and batch potency can vary, it can produce more T3-driven side effects than pure T4 at equivalent 'grain' doses.
02 Mechanism
Supplies exogenous T4 and T3 that bind nuclear thyroid receptors, raising basal metabolic rate, thermogenesis and lipolysis; supraphysiologic doses suppress TSH via feedback.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Cutting (off-label) | 1–3 grain/day | Oral | Supraphysiologic; titrate, monitor heart rate |
| Replacement | 30–120 mg/day | Oral | ~0.5-2 grains; 1 grain ~65 mg = ~38 mcg T4 + ~9 mcg T3 |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Increased metabolic rateCombined T4/T3 raises energy expenditure in a deficit. | Raised BMR | Clinical | |
| Symptom relief in hypothyroidismRestores energy and thermogenesis in genuine deficiency. | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| TachycardiaElevated heart rate and palpitations from the T3 fraction. | Moderate | At high doses | Clinical | |
| Batch potency variabilityHormone content can vary between batches and brands. | Moderate | Product-dependent | Observational | |
| Muscle catabolismLean-mass loss when supraphysiologic and hypocaloric. | Moderate | In deficit | Clinical |