When Should I Do My Bloodwork if My Cycle Is Irregular

Question:
I’m new to BHRT and was told bloodwork is best done on days 19–21 of my cycle. My cycles have also been inconsistent—regular for several months, then missed or spotty. Is my cycle considered irregular, and when should I do my bloodwork for the most accurate results?

Answer:
This is a very common and important question—especially for first-time BHRT patients.

Is my cycle considered irregular?

Yes. A cycle may be considered irregular if:

• Periods are occasionally missed

• There is spotting instead of a full period

• Cycle length varies significantly month to month

Even if you previously had several regular months, recent skipped or irregular bleeding patterns suggest that ovulation timing may be inconsistent.

Why do we recommend days 19–21?

For individuals with regular cycles, days 19–21 typically reflect the luteal phase, when progesterone levels peak. Testing during this window provides the most clinically useful information for BHRT planning.

What if my cycles are irregular or I can’t test on days 19–21?

If cycles are irregular—or if you are unavailable during days 19–21—we usually recommend one of the following:

• Waiting for your next cycle and testing when timing can be optimized

• Testing based on symptoms rather than cycle day, if periods are unpredictable

• Using a standardized testing window recommended by your Nurse Practitioner for irregular cycles

The goal is to collect results that best reflect how your hormones are functioning overall, not just on a calendar date.

What is the best next step?

The most accurate timing depends on your individual cycle pattern and symptoms. We strongly recommend:

• Booking your bloodwork using our scheduling tool:
  ? https://hormone-and-blood-work-scheduler.onrender.com/

• Reviewing your cycle history with your Nurse Practitioner, who can determine the most appropriate timing and interpret results correctly in the context of cycle variability.