Hormone Labs Broken Down : FSH, LH, Estradiol, Progesterone
Fatigue, irregular cycles, PMS, sleep issues, weight changes… these symptoms are real, and your labs often hold important clues. The key is knowing how to interpret them in context.
Let’s break down four of the most commonly tested hormones and what they actually tell us about your body.
FSH (Follicle Stimulating Hormone)
FSH is a hormone released by your brain (specifically the pituitary gland) that tells your ovaries to mature follicles at the start of your cycle leading to Estrogen production.
What it helps us understand
Ovarian reserve (how your ovaries are functioning)
Communication between your brain and ovaries
Clinical Implications
During perimenopause , FSH gradually rises as Estrogen levels decline.
In conditions such as primary ovarian insufficiency we see a high FSH and a low Estradiol level
We see this pattern in Hypothalamic Amenorrhea which can be caused by high stress levels, inadequate nourishment, and female athlete triad.
When it’s typically tested
Early in the cycle (days 2–4)
LH (Luteinizing Hormone)
LH is released by the brain ( also the pituitary gland) to trigger ovulation. This also leads to progesterone production in the second half of the cycle ( the luteal phase)
Clinical Applications
Track ovulation - whether you are trying to understand your hormone cycle better or trying to get pregnant
monitor PCOS - a higher LH compared to FSH is seen in PCOS
Estradiol (E2)
Estradiol is the primary form of estrogen during your reproductive years. It’s produced by developing follicles in the ovaries.
When its measured
Cycle days 2-4 for baseline level
Cycle day 12 ( right before ovulation ) : peak Estradiol levels
Cycle Day 21 ( middle of luteal phase) : second Estradiol peak
Clinical Applications
assess ovarian function and follicle development
If Estradiol does not peak , LH does not rise and ovulation does not occur
high Estradiol during luteal phase can contribute to PMS symptoms
low Estradiol levels can cause decreased bone density, infertility, fatigue, and vaginal dryness.
Estradiol levels can rise and fall unpredictably during perimenopause causing vasomotor symptoms, vaginal dryness, UTI’s, yeast infections , migraines, mood swings, etc.
Progesterone
Progesterone is often called the “calming” hormone—and for good reason.
It rises after ovulation and is essential for:
Supporting implantation when trying to conceive
Regulating mood
Promoting restful sleep
Stabilizing your endometrium - When progesterone levels decline , this triggers your period to start.
When it’s tested
7 days after ovulation (on cycle day 21 if you have a regular, 28 day cycle)
Clinical Applications
confirms if ovulation happened
Progesterone levels start to decrease first in perimenopause. Progesterone replacement helps with anxiety and insomnia during perimenopause.
Low progesterone levels can cause heavy bleeding during your periods
Low progesterone is associated with luteal phase defect and PMS symptoms
Want Help Interpreting Your Labs?
If you’ve had testing done and aren’t getting clear answers—or you’re dealing with symptoms that aren’t improving—there’s often more to uncover.
A more comprehensive, root-cause approach can help connect the dots and create a plan that actually supports your body.
