Estradiol (E2) Blood Test

The Estradiol (E2) Test measures the most bioactive estrogen. Produced primarily in the ovaries (with minor contributions from other tissues), E2 supports reproductive function, bone and brain health, weight balance, and thyroid interplay. Most circulating E2 is protein-bound; clinical labs typically report total estradiol.

Why Measure Estradiol?

Cycle mapping: E2 rises pre-ovulation and varies across the cycle.
Fertility & symptoms: Helps evaluate irregular periods, perimenopause, and menopausal symptoms.
Bone & metabolic context: Low E2 can affect bone and metabolic health over time.

Preparation & Timing

Many clinicians prefer sampling on cycle days 2–5 for baseline E2 (follicular phase). Note cycle day and hormones/medications. No routine fasting required.

Understanding Results (High-Level)

Follicular: Lower baseline.
Pre-ovulatory surge: Higher values.
Post-menopause: Lower levels typical.

How the PlexusDx Test Works

At-home collection.
prepaid return mailer.
Results in ~2 business days after lab receipt.
Order direct; HSA/FSA eligible.

FAQs

On HRT? Timing relative to the last dose can influence levels—follow your prescriber’s guidance.

Biotin supplements? High-dose biotin may interfere with some immunoassays; consult with your provider and discuss supplements before testing.