10/21/2026
When it comes to hormone testing, one of the most important things to understand is that timing matters.
Our hormones fluctuate throughout the menstrual cycle, which means testing on the wrong day can give us an incomplete or misleading picture of what’s happening in the body.
For example, progesterone is naturally low during the follicular phase and rises after ovulation. So, testing progesterone on cycle day 5, 6, or 7 isn’t going to tell us much about whether you’re producing adequate progesterone after ovulation.
When evaluating hormonal health and fertility, we often recommend testing at specific times:
* Cycle Day 3: To evaluate baseline hormones such as FSH, LH, and estradiol.
* Approximately 7 days after ovulation: To evaluate progesterone during the mid-luteal phase. This is often called “day 21 testing,” but only applies if you ovulate around day 14.
Another important factor? Hormones don’t remain constant throughout the day. Many are released in pulses or follow daily rhythms, meaning blood levels can fluctuate depending on when they’re measured.
Blood Testing vs. DUTCH Urine Testing
Both can provide valuable information, but they tell us different things.
Serum blood testing measures circulating hormone levels at a specific point in time. However, it doesn’t provide a detailed picture of how those hormones are being metabolized and eliminated from the body.
This is where testing like the DUTCH can provide additional insight.
By collecting multiple urine samples throughout the day, we can evaluate hormone metabolites and gain insight into how the body is processing estrogens, androgens, progesterone, and cortisol.
We can also look at estrogen metabolism pathways and markers related to phase 1 and phase 2 metabolism, which help us better understand how hormones are being broken down and processed.
So, which test is better?
Neither is necessarily better. They serve different purposes and can complement one another.
The key is understanding what we’re testing, why we’re testing it, and WHEN we’re testing it.