Blood Tests for Perimenopause: What to Ask Your Doctor and What the Results Mean

Testing has limits, but it still matters

One of the most frustrating things you can hear when you suspect perimenopause is that blood tests cannot confirm it. That is technically true because hormone levels fluctuate so much during this transition that a single test can look entirely normal one week and very different the next.

But this does not mean testing has no value. Blood tests can rule out other conditions with overlapping symptoms, give useful context when results are interpreted alongside your symptoms, identify deficiencies that are contributing to how you feel, and provide a baseline that makes future comparisons meaningful. Knowing what to ask for, and why, helps you get more out of your appointments.

The key hormones to test and why

FSH (follicle-stimulating hormone) is the test most commonly associated with perimenopause diagnosis. FSH rises as the ovaries become less responsive, and a consistently elevated FSH is one marker of the transition. However, FSH fluctuates during perimenopause, so one normal reading does not rule it out, and one elevated reading is not definitive on its own.

Estradiol is the main form of estrogen measured in blood tests. Low estradiol alongside high FSH suggests advancing perimenopause. However, because estradiol fluctuates so much in early perimenopause, this test alone is often inconclusive.

LH (luteinizing hormone) is another pituitary hormone that rises as ovarian function declines. It is often tested alongside FSH.

Testosterone, both total and free, is worth requesting if you are experiencing symptoms of low libido, fatigue, and reduced motivation. Female reference ranges are not as well-established as male ones, so results need to be interpreted by a provider familiar with women's hormonal health.

Progesterone testing in the mid-luteal phase (around day 21 of a 28-day cycle) can confirm whether ovulation is occurring. Consistently low progesterone in this window is consistent with anovulatory cycles, which are common in perimenopause.

Tests that go beyond hormones

A thorough blood workup for perimenopause symptoms should include more than just hormones. Several other markers are worth checking.

Thyroid function (TSH and free T4) is essential because thyroid conditions are more common in women during midlife and their symptoms, including fatigue, weight changes, brain fog, anxiety, hair loss, and mood shifts, overlap closely with perimenopause. Many women are told their symptoms are hormonal when thyroid dysfunction is the primary driver.

Vitamin D is frequently deficient and contributes to fatigue, mood changes, bone vulnerability, and immune function. Testing your level is the only way to know where you stand, and supplementing to adequacy is straightforward once you have that information.

Full blood count (CBC) screens for anemia, which causes fatigue and can worsen exercise intolerance. Heavy perimenopausal periods are a common cause of iron deficiency in this age group.

Fasting glucose and HbA1c give a picture of blood sugar regulation, which becomes more important during perimenopause as insulin sensitivity can shift with declining estrogen.

What to bring to your appointment

Walking into a blood test conversation prepared makes a significant difference. Write down your symptoms and when they occur, note any changes in your cycle (length, flow, frequency), and be specific about which symptoms are affecting your quality of life most.

Ask for the tests you want by name, especially if your provider does not routinely offer them. It is reasonable to ask for FSH, estradiol, TSH, vitamin D, full blood count, and fasting glucose at a minimum. Depending on your symptoms, testosterone and progesterone may also be relevant.

Ask for a copy of your results. Many people leave appointments with only a verbal summary and no numbers to refer back to. Having the actual values and reference ranges helps you track change over time and supports better conversations at future appointments.

Understanding your results

Reference ranges on lab reports are based on population averages and do not always reflect what is optimal for you individually. A result labeled normal can still be at the low end of normal in a way that is meaningful for your symptoms.

For FSH, a level above 10 IU/L starts to suggest some ovarian aging is occurring. A level consistently above 25 to 40 IU/L in the setting of missed periods and symptoms is more strongly consistent with advanced perimenopause. But the range varies widely between labs.

For vitamin D, a blood level of 50 to 80 nmol/L is often considered adequate, but some providers aim higher. Ask what your provider considers a good target and whether supplementation makes sense given your level.

For thyroid, TSH within the lab normal range can still be suboptimal for some people. If your TSH is in the high-normal range and you have symptoms consistent with hypothyroidism, that conversation is worth having.

When results are normal but you still feel awful

Normal results are genuinely frustrating when you feel far from normal. This experience is common and valid. Laboratory tests measure what is happening at one moment in a transition characterized by constant change.

If your test results come back normal but your symptoms are significant, you have a few options. Ask for repeat testing, ideally at different points in your cycle. Ask whether your symptoms, taken together, are consistent with perimenopause even without abnormal tests. Ask whether a trial of treatment based on your clinical picture rather than test results is appropriate. Many knowledgeable providers will treat perimenopause based on symptoms when labs are inconclusive, because the hormonal fluctuations of early perimenopause often produce real symptoms before numbers go outside range.

You are not making this up. Your experience is real, and your provider should take it seriously alongside any test results.

How to monitor changes over time

Blood tests are most useful when they are part of an ongoing picture rather than a one-time check. Getting a baseline set of results, then rechecking key markers every one to two years, helps you and your provider track the trajectory of your transition.

Alongside blood testing, tracking your symptoms consistently gives you a record that is often more informative than any single test result. When you log how you feel over weeks and months, patterns emerge. You may notice that certain symptoms cluster at particular points in your cycle, or that they have changed in character over time.

PeriPlan lets you log symptoms and track patterns over time, building the kind of longitudinal record that makes blood test conversations richer and more productive. Bring that data to your appointments.

This content is for informational purposes only and does not replace medical advice. Always consult your healthcare provider about your specific situation.