Menopause is not a light switch that flips from one day to the next. It is a gradual process spanning years, during which your hormonal balance shifts step by step. Understanding which hormones change and in what order can help you make sense of what is happening and decide when testing is worthwhile.
Menopause in phases
What we call menopause actually consists of three overlapping phases:
- Perimenopause - the lead-up to menopause, when hormones begin to fluctuate. This can start around age 40, sometimes earlier, and lasts an average of four to eight years.
- Menopause - the point at which you have gone twelve consecutive months without a period. This is technically a single moment, confirmed only in retrospect.
- Post-menopause - all years after menopause. Hormone levels stabilise at a new, lower baseline.
The average age of menopause in the Netherlands is 51, but anywhere between 45 and 55 is normal. Genetics, smoking, BMI and ethnicity all influence the timing.
FSH: the first indicator
FSH (follicle-stimulating hormone) is often the first blood value to change. As your ovaries become less responsive, the pituitary produces more FSH to compensate. In fertile years, FSH is typically below 10 IU/L (measured on cycle day 2-5). During perimenopause it can rise to 15-25 IU/L, and after menopause it stabilises above 30-40 IU/L.
However, FSH can fluctuate considerably during perimenopause. One month it may be elevated, the next completely normal. The pattern across multiple measurements is often more informative than a single result.
Oestradiol: the declining key hormone
Oestradiol (E2) is the most active form of oestrogen and influences bone density, cardiovascular health, skin, mood, sleep and cognitive function. During perimenopause it swings erratically, sometimes spiking higher than before, then dropping sharply. These fluctuations drive many classic symptoms: hot flushes, night sweats, mood swings and sleep problems.
After menopause, oestradiol stabilises below approximately 100 pmol/L. While this lower level is a normal part of post-menopause, it can have long-term implications for bone health and cardiovascular risk.
Progesterone: often the first to decline
Progesterone is produced primarily after ovulation. When ovulation becomes irregular early in perimenopause, progesterone production is the first to drop, often even before FSH rises noticeably. A relative progesterone deficiency compared to oestrogen can cause heavier periods, bloating, breast tenderness, irritability and sleep problems, particularly difficulty staying asleep.
LH: partner of FSH
LH (luteinising hormone) works closely with FSH. During menopause LH rises gradually but typically less dramatically than FSH. The FSH-to-LH ratio can provide additional context: a ratio above 1.5-2 suggests declining ovarian function.
Recognising your phase
In early perimenopause, cycles shorten or become irregular, progesterone drops, and FSH may still be normal. In late perimenopause, you experience longer gaps without periods, clearly elevated FSH, dropping oestradiol, and prominent symptoms. After menopause, hormone levels are stably low and symptoms gradually ease over two to five years for most women.
What do fluctuating values mean?
One of the most frustrating aspects of perimenopause is that blood values can differ significantly from month to month. A single snapshot does not always tell the full story. The pattern across two or three measurements, spaced a few months apart, is more reliable. Always combine your blood values with your symptoms and how you feel. An experienced doctor looks at the whole picture, not just individual numbers.
When to test
Good reasons include irregular cycles, menopausal symptoms such as hot flushes or sleep problems, suspicion of early menopause before age 45, considering hormone therapy, persistent complaints despite being told everything is "normal", or wanting a baseline measurement around age 40. If you still menstruate, days 2-5 of your cycle are most suitable for FSH, LH and oestradiol. Progesterone is best measured around day 19-22.
Frequently asked questions
Can I be in menopause at 38?
Yes, though it is uncommon. Premature ovarian insufficiency (POI) affects about 1% of women and has implications beyond fertility: early loss of oestrogen increases the risk of osteoporosis and cardiovascular disease. If you are under 40 with menopausal symptoms, having your hormones tested is especially important.
How often should I test during menopause?
There is no fixed frequency. An initial measurement provides a baseline. If you start hormone therapy or adjust your lifestyle, retesting after three to six months is sensible to see how your values respond. Some women choose annual checks for peace of mind. In post-menopause, routine testing is usually unnecessary unless you are on hormone therapy and want to evaluate your dosage.
What if my values are normal but I do not feel well?
Reference ranges are broad and based on large populations. Your personal optimum may differ from what the lab defines as "normal". Moreover, hormones fluctuate, so today's measurement is a snapshot that could look very different in two weeks. Take your symptoms seriously, even if the numbers look fine on paper. Discuss both results and symptoms with a doctor experienced in hormonal health. Sometimes retesting after a few months is worthwhile to see the pattern.
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