Is a sustained progesterone metabolite (PdG) level of 20 and increasing estrogen metabolite (E1G) levels from 110.5 to 128.4 to 196.6 at 11-13 days past initial luteinizing hormone (LH) surge, while taking progesterone supplementation, indicative of early pregnancy or a normal luteal phase in a patient on cycle day (CD) 24-26?

Hormone Pattern Analysis: Early Pregnancy vs Normal Luteal Phase

Your rising E1G pattern (110.5 → 128.4 → 196.6) at 11-13 days post-LH surge, combined with sustained PdG of 20 while on progesterone supplementation, is more consistent with early pregnancy than a normal luteal phase. 1, 2

Key Distinguishing Features

Normal Luteal Phase Patterns

• E1G typically remains relatively stable or declines during the mid-to-late luteal phase in non-conception cycles 1, 2
• In normal ovulatory cycles, estrone-3-glucuronide (E1G) shows correlation with plasma estradiol but does not demonstrate the progressive rise you're experiencing 2
• The midluteal phase (progestation) is characterized by PDG ≥10 μg/mg Cr with relatively stable hormone levels, not rising estrogen 1

Early Pregnancy Patterns

• Progressive E1G elevation is characteristic of early pregnancy as the corpus luteum is maintained and stimulated by hCG 1, 2
• Your E1G nearly doubled from 110.5 to 196.6 over just 2 days (CD 24 to CD 26), which represents a 78% increase 2
• The sustained PdG of 20 throughout this period, despite progesterone supplementation, suggests adequate corpus luteum function 1, 3

Critical Interpretation Points

Progesterone Supplementation Confounds PdG Interpretation

• Your exogenous progesterone prescription makes PdG levels less interpretable for distinguishing pregnancy from luteal phase 1, 3
• The stable PdG of 20 could reflect either endogenous production plus supplementation or supplementation alone 3
• In normal cycles without supplementation, PDG levels in the 95th percentile decline steadily across the luteal phase 3

E1G is the Discriminating Factor

• The rising E1G pattern is the most informative marker in your case, as it is not affected by progesterone supplementation 1, 2
• E1G levels were lower in anovulatory cycles compared to ovulatory cycles, and your sustained elevation confirms ovulation occurred 3
• The progressive increase rather than plateau or decline strongly suggests early pregnancy 1, 2

Recommended Next Steps

Immediate Testing

• Obtain a serum β-hCG test immediately to definitively confirm or exclude pregnancy 4
• A urine pregnancy test (home test) can provide rapid preliminary information if serum testing is not immediately accessible 4
• Timing is appropriate: at 13 days post-LH surge (approximately 11-12 days post-ovulation), hCG should be detectable if pregnancy has occurred 4

Continued Monitoring

• Continue progesterone supplementation until pregnancy status is confirmed, as abrupt discontinuation could compromise a potential early pregnancy 5
• If pregnancy is confirmed, progesterone support is often continued through the first trimester in assisted reproduction contexts 5
• If pregnancy is not confirmed, expect menstruation within 2-4 days after progesterone discontinuation 5

Important Caveats

Timing Considerations

• Your LH surge occurred on CD 13 (evening), making ovulation likely on CD 14-15 4, 6
• At CD 26 (13 days post-LH surge), you are approximately 11-12 days post-ovulation, which is late luteal phase 4, 1
• This timing makes the rising E1G pattern even more significant, as normal luteal phase E1G should be declining by this point 1, 2

Avoid Common Pitfalls

• Do not assume the stable PdG indicates normal luteal phase when you are taking exogenous progesterone 1, 3
• Do not wait for missed menses to test for pregnancy, as early confirmation allows appropriate management decisions 4
• Do not discontinue progesterone supplementation before confirming pregnancy status if there is any possibility of conception 5