E1G and PDG Levels at 7DPO During Letrozole Treatment
Your E1G level of 100 and PDG level of 20 at 7 days post-ovulation does not represent a hormonal imbalance—these values reflect the expected hormonal profile during letrozole-assisted ovulation with progesterone supplementation.
Understanding Your Hormone Levels in Context
Letrozole's Effect on Estrogen Metabolism
Letrozole significantly suppresses estradiol (E2) levels during both the follicular and luteal phases, with studies showing E2 reductions of approximately 58% during follicular phase and 39% during luteal phase compared to standard ovulation induction 1.
The aromatase inhibitor mechanism blocks conversion of androgens to estrogens, which explains your relatively modest E1G (estrone metabolite) level 2.
This estrogen suppression is intentional and therapeutic when using letrozole for ovulation induction, as it maintains estrogen near physiologic ranges while still achieving successful follicular development 3.
Progesterone Supplementation Context
Your PDG level of 20 reflects both endogenous corpus luteum production and exogenous progesterone supplementation, making direct comparison to non-supplemented cycles inappropriate 4.
Progesterone levels remain elevated during the luteal phase even with letrozole use, as letrozole primarily affects estrogen synthesis rather than progesterone production 4.
Studies demonstrate that letrozole-associated cycles maintain adequate corpus luteum function, with some evidence suggesting improved luteal phase progesterone output when letrozole is used 1.
Why This Is Not an Imbalance
The Estrogen-Progesterone Ratio
The traditional concept of "estrogen dominance" or hormonal imbalance doesn't apply in medically-assisted cycles where intentional pharmacologic manipulation of hormone levels is the therapeutic goal 3.
Letrozole maintains adequate endometrial development even at high doses despite lower estrogen levels, indicating that the absolute estrogen level is less critical than estrogen receptor availability 5, 6.
Expected Hormonal Profile
Your hormone pattern is consistent with successful letrozole-mediated ovulation: suppressed estrogen with maintained progesterone production 1.
The altered balance between estrogens and androgens is a known and expected effect of aromatase inhibition, reflected in changes to sex hormone binding globulin (SHBG) throughout the luteal phase 1.
Clinical Implications
Monitoring Considerations
Ultrasound monitoring during treatment cycles is essential to confirm appropriate follicular development and endometrial thickness, which are more clinically relevant than isolated hormone measurements 5, 6.
Endometrial thickness assessment is more predictive of cycle success than absolute hormone levels when using letrozole, as the medication maintains adequate endometrial development 7.
Treatment Duration
Continue letrozole treatment for 3-6 cycles before considering the regimen unsuccessful, as recommended by the American College of Obstetricians and Gynecologists 5, 6.
If pregnancy is not achieved after 3-6 cycles, adding intrauterine insemination (IUI) to letrozole treatment is the next appropriate step rather than adjusting hormone levels 5, 8.
Common Pitfalls to Avoid
Do not attempt to "correct" estrogen levels during letrozole treatment, as the suppressed estrogen is the intended mechanism of action 2, 3.
Do not compare your hormone levels to reference ranges from natural cycles or standard IVF protocols, as letrozole fundamentally alters the hormonal milieu 1, 9.
Do not discontinue progesterone supplementation based on PDG measurements alone, as luteal phase support is standard practice regardless of measured progesterone metabolite levels 4.