Are Blood Tests Important?

Finding the optimal dose of Hormone Replacement Therapy (HRT) for a woman, can bring significant relief for women navigating perimenopause and menopause, however, how crucial blood testing is in finding this individualized ‘optimal dose’ often sparks debate.  Some practitioners rely heavily on lab results to guide treatment, while others focus primarily on symptoms and may forgo testing altogether. So, which approach is best?  

In reality, a woman’s symptomology is always the most important factor in guiding treatment, however, when timed appropriately, lab testing can offer very helpful insights when assessing and monitoring treatment.

Reasons TO DO Hormone Lab Testing:

• Blood work can offer invaluable insight into why a woman is having particular symptoms and identify which hormones may need more support.  
• It can reduce some of the guess work when formulating a woman’s individualized hormone regime- particularly if she is presenting with a more complicated hormone picture. 
• It provides a baseline, which is helpful when comparing hormone changes and progress once starting HRT.
• Blood work indicates what the ovaries are up to and how far along a woman is in their hormonal transition.  For example, FSH and LH can indicate if she is in early or late perimenopause, or in menopause, which has direct correlations to weight loss resistance. 
• Blood work confirms absorption with creams, gels, or patches and ensures the treatment is working effectively.
• It is helpful for monitoring the ratio between estrogen, progesterone, and testosterone which is essential to ensure doses are at an optimal level for overall health.

Reasons Some doctors do not want to do Hormone Lab Testing:

• A one-time snap shot for hormone lab testing is not always reliable because a woman’s hormone levels can fluctuate dramatically from day to day, particularly in perimenopause, making a single blood test a poor reflection of her true hormonal picture.   This factor is mitigated if she goes on day 3 or day 21 of her cycle (see more on this below).  
• Lab ranges reflect averages, not what is optimal for each individual woman.  For example, being in the bottom 10% of the range may be reported as normal on a woman’s blood test, but the value may not be optimal for her. Not all doctors have extra training in hormone lab interpretation, so it is very important to find a doctor who knows key markers to look for in lab results and what is considered optimal for her age, life stage etc.  

How to Maximize the Accuracy (and Helpfulness) of your Hormone Blood Tests

1. The timing of the blood testing matters!
   1. Testing around day 3 of the menstrual cycle provides a baseline view of ovarian function and estrogen production, while testing around day 21 (or about a week after ovulation) gives a clearer picture of progesterone levels and luteal phase balance.  Note: If your periods are really irregular and you do not know when you are ovulating or when day 3 or day 21 is of your cycle, your hormone doctor can guide you on when best to do a blood test.  

• Avoid applying Estradiol to arms right before a blood test.  If you apply estrogen to your inner arms and then have blood drawn shortly after, from the same inner arm area, your results will very likely appear falsely high. This happens because the hormone is still concentrated in the skin and bloodstream at the application site. Tip: Apply estrogen to the thighs or buttockson blood test days, or simply wait untilafter your blood draw to apply it.

• Repeating these tests, every 3-6 months, under the right conditions, allows doctors to identify patterns, and hormonal transitions, rather than relying on one single snapshot. 

Key Hormones to Test in Perimenopause (I find these tests extremely helpful, but you may have to ask your doctor to test all of these-they may not include them all unless you ask).

Hormone	What It Measures	Why It Matters
Estrogen	Levels of circulating estrogen	Helps explain hot flashes, weight changes, heavy bleeding, or estrogen dominance.
Progesterone	Confirms ovulation and luteal phase balance	Essential for mood, sleep, and regulating estrogen’s effects.
Free Testosterone	Active, unbound testosterone	Impacts energy, libido, muscle strength, and cognition.
FSH & LH	Brain signals stimulating ovarian function	Indicates ovarian reserve and where you are in the menopausal transition.
SHBG (Sex Hormone Binding Globulin)	Protein that binds sex hormones	Controls how much free estrogen and testosterone are available for use.
DHEA-S	Adrenal androgen and hormone precursor	Reflects adrenal health and resilience; contributes to estrogen and testosterone production.
TSH (thyroid)	Thyroid gland activity	Affects energy, mood, metabolism, and weight—imbalances can mimic perimenopausal symptoms.

Bottom Line: The Role of Regular Review and Hormone Testing

A woman’s hormones are in flux during perimenopause, so HRT isn’t a “set it and forget it” therapy. Regular check-ins with your hormone doctor is essential in order to monitor symptoms, get follow up blood testing and adjust dosing as needed.  

While how a woman feels is always the most important factor in guiding treatment, blood work, taken at the right time in her cycle can add extremely valuable insights.