- Definition
Bioidentical
Structurally identical, at the molecular level, to a hormone the human body produces. 17-beta-estradiol and micronized progesterone are bioidentical. Conjugated equine estrogens (Premarin) and medroxyprogesterone acetate are not bioidentical.
FDA-approved bioidentical HRT exists
This is the part most marketing leaves out. Estradiol patches, gels, creams, sprays, and pills, and oral micronized progesterone (Prometrium), are FDA-approved AND bioidentical. They are the most studied form of HRT and the standard of care in NAMS guidance. There is no clinical reason to default to compounded preparations when FDA-approved bioidenticals deliver the same molecules with documented manufacturing standards.
Comparison
| Bioidentical? | FDA-approved? | Pharmacy | Evidence | Typical use | |
|---|---|---|---|---|---|
| Estradiol patch / pill / gel | Yes | Yes | Commercial | Strong (RCTs) | First-line systemic estrogen |
| Micronized progesterone (Prometrium) | Yes | Yes | Commercial | Strong (RCTs) | First-line progestogen with uterus |
| Conjugated equine estrogens (Premarin) | No | Yes | Commercial | Strong but older trials (WHI) | Less commonly first-line today |
| MPA (Provera) | No | Yes | Commercial | Strong but unfavorable breast safety vs progesterone | Rarely first-line today |
| Compounded estradiol+progesterone (often called BHRT) | Yes | No | 503A pharmacy | Indirect (no large RCTs of compounded specifically) | Used when commercial doses or routes don't fit |
| Pellets (testosterone, estradiol) | Yes | No (compounded) | 503A pharmacy | Moderate | Quarterly dosing convenience; cannot be removed if dose is wrong |
What 'compounded BHRT' actually offers
Compounded BHRT is genuinely useful in narrow contexts: when the commercial dose options do not fit, when a patient cannot tolerate excipients in commercial products, or when a unique combination is needed. Beyond those cases, compounded preparations are not 'safer' or 'more bioidentical' than FDA-approved bioidentical HRT, despite marketing claims that imply otherwise.

