Target Ranges (E2, T, E1, SHBG)
Primary Targets
The following targets are based on Endocrine Society guidelines and WPATH SOC8 recommendations:
| Hormone | Target Range | Why |
|---|---|---|
| Estradiol (E2) | 100–200 pg/mL (367–734 pmol/L) | Feminisation, bone health, T suppression |
| Testosterone (T) | < 50 ng/dL (< 1.73 nmol/L) | Suppress masculine traits |
| SHBG | 40–120 nmol/L (normal); > 150 nmol/L indicates excess binding | High SHBG binds free hormones, reducing effectiveness |
Secondary Targets
| Hormone | Target Range | Notes |
|---|---|---|
| Estrone (E1) | Not routinely needed | WPATH SOC8 states E1:E2 ratios need not be measured. Recent evidence does not support the claim that high E1:E2 ratios impair feminisation. Switching to parenteral routes avoids high E1. |
| Free T | Below female range upper limit | Roughly < 3 ng/dL |
| DHT | < 10 ng/dL | May be relevant if hair loss continues despite low T |
| LH | < 2 IU/L | Confirms HPG axis suppression |
| FSH | < 2 IU/L | Confirms HPG axis suppression |
Understanding the Numbers
Estradiol (E2)
| Level | Interpretation | Action |
|---|---|---|
| < 50 pg/mL | Ineffective | Increase dose |
| 50–100 pg/mL | Suboptimal | Increase dose |
| 100–200 pg/mL | Optimal target | Maintain |
| 200–300 pg/mL | Elevated but acceptable (monotherapy) | OK if T is suppressed and SHBG normal |
| > 300 pg/mL (trough) | Excessive | Reduce dose (unless monotherapy and well-tolerated) |
Testosterone (T)
| Level | Interpretation | Action |
|---|---|---|
| > 200 ng/dL | Not suppressed | Increase AA or E2 |
| 100–200 ng/dL | Partially suppressed | Increase AA |
| 50–100 ng/dL | Borderline | Consider increasing AA |
| < 50 ng/dL | Target achieved | Maintain |
| < 20 ng/dL | Fully suppressed (fine) | Could try reducing AA if side effects |
How Route Affects Levels
| Route | Typical E2 at Standard Dose | E1:E2 Ratio | SHBG Impact |
|---|---|---|---|
| Oral pills | 30–60 pg/mL per 2 mg | ~5:1 (high E1) | Raises SHBG |
| Sublingual | 80–200 pg/mL per 2 mg | ~1:1 | Moderate SHBG rise |
| Transdermal patches | Steady 50–150 pg/mL | ~0.5:1 (lower E1) | Minimal SHBG rise |
| Gel | Steady 50–150 pg/mL | ~0.5:1 | Minimal SHBG rise |
| Injectable EV | Peak high, trough variable | ~0.5:1 | Minimal SHBG rise |
Target Timing
When to Test
Always test at trough — the lowest point in your dosing cycle:
| Route | Trough Is |
|---|---|
| Oral/sublingual (daily) | Just before next dose (e.g., morning before taking pills) |
| Transdermal patches | Day of change (just before applying new patch) |
| Gel | Before morning application |
| Injectable EV | Day 5 (just before next injection) |
| Injectable EC | Day 7 |
| Injectable EEn | Day 7 |
The Problem with High SHBG
SHBG binds to sex hormones and makes them inactive. High SHBG can mean:
- High total E2 but low free E2 (less feminisation)
- High total T (from bicalutamide) but low free T (good, actually)
- Insensitivity to dose increases — more E2 just raises SHBG further
Causes of High SHBG
- Oral estrogen (especially at high doses)
- Genetics
- Thyroid conditions
- Liver conditions
- Low androgen levels
What to Do About High SHBG
| SHBG Level | Recommendation |
|---|---|
| < 80 nmol/L | Normal; no action needed |
| 80–150 nmol/L | Mild elevation; monitor |
| > 150 nmol/L | Consider switching from oral to transdermal/injectable E2 |
When Targets Don't Tell the Whole Story
Some trans women have levels in target range but see poor feminisation. Possible reasons:
- High SHBG — free hormones too low (see above)
- Slow response genetics — some people are just slow responders
- Androgen receptor sensitivity — rare; some people are hypersensitive to residual androgens
- Progesterone needed — may help breast maturation
- Too early — HRT takes years, not months
Conversely, some trans women see good changes at E2 levels below 100 pg/mL. Targets are guidelines, not absolute rules.
References
Hembree WC, et al. (2017). Endocrine Treatment of Gender-Dysphoric/Gender-Incongruent Persons: An Endocrine Society Clinical Practice Guideline. JCEM, 102(11):3869–3903. https://academic.oup.com/jcem/article/102/11/3869/4157558
Coleman E, et al. (2022). Standards of Care for the Health of Transgender and Gender Diverse People, Version 8. International Journal of Transgender Health, 23(S1). https://www.tandfonline.com/doi/full/10.1080/26895269.2022.2100644
UCSF Transgender Care. Feminising hormone therapy — monitoring. https://transcare.ucsf.edu/guidelines