Perimenopause and hormonal health: the functional medicine assessment

What perimenopause actually is

Perimenopause is not low oestrogen. That is the misunderstanding behind most of the poor advice, and most of the unhelpful testing, in this area.

It is the transition, usually starting in the early to mid forties and lasting anywhere from a couple of years to nearly a decade, during which the ovaries become less predictable. Progesterone falls first, because cycles without ovulation become more common, and a cycle without ovulation produces no progesterone at all. Oestrogen does not decline smoothly. It swings, often to levels higher than earlier in life before crashing, and the swings produce many of the symptoms. Menopause itself is a single day, twelve months after the last period. Everything before it is perimenopause, and everything after it is postmenopause.

The consequence for testing is direct. A blood test measures one moment in a system that is fluctuating week to week. NICE guideline NG23, updated in November 2024, says that in women over forty-five perimenopause and menopause should be diagnosed on symptoms alone, without laboratory tests. Between forty and forty-five, an FSH test may be considered; under forty, where premature ovarian insufficiency is the concern, two FSH levels taken weeks apart are needed. Anyone offering you a hormone panel to 'confirm' perimenopause at forty-eight is either unaware of the guidance or ignoring it.

The symptoms are wider than hot flushes, and the ones that bring people to me are usually the others:

• Sleep that breaks at three or four in the morning, with or without night sweats
• Anxiety, low mood, irritability, or a loss of resilience that feels unlike you
• Brain fog: word-finding, concentration, holding a thread. This is the symptom that frightens people, and the one most often mistaken for early dementia
• Joint and muscle aches, sometimes labelled fibromyalgia
• Palpitations, which are frequently investigated by cardiology and found to be nothing cardiac
• New or changed migraine
• Heavier, closer or more erratic periods, and the iron deficiency that follows
• Weight gain around the middle despite no change in habits, and rising cholesterol
• Vaginal dryness, urinary symptoms and recurrent urinary infections
• Loss of libido

Several of those are also the symptoms of thyroid disease, iron deficiency, sleep apnoea, insulin resistance and depression, all of which become more common in the same decade. That overlap is the reason a symptom checklist is not enough on its own, and it is the reason for the assessment below.

What a functional medicine assessment covers that a standard review does not

A good GP menopause review, done according to NICE, covers symptoms, medical history, contraception, cardiovascular risk and a discussion of HRT. Where it is done well it is excellent. Where it goes wrong is usually one of two ways: a ten-minute appointment in which the symptoms are attributed to stress, or a prescription for HRT with nothing else looked at, so that the woman who is also hypothyroid, iron deficient and not sleeping stays unwell and concludes HRT does not work.

What I do is longer and wider. The table sets out the difference honestly, including the tests I do not think earn their place.

Where HRT fits, and what sits alongside it

The evidence for HRT has been through a long correction since the Women's Health Initiative results of 2002 frightened a generation of women and doctors away from it. The re-analyses of that trial, and the guidance that followed, support a clearer position: for most women under sixty, or within ten years of menopause, the benefits of HRT for symptoms outweigh the risks, and the risks are smaller than was believed. NICE NG23 recommends HRT as the first-line treatment for hot flushes and night sweats, and the 2024 update added cognitive behavioural therapy as an option alongside or instead of it, for vasomotor symptoms, sleep and mood.

The modern regimens matter. Transdermal oestradiol, as a patch, gel or spray, does not carry the increased clotting risk of oral oestrogen. Micronised progesterone is better tolerated and appears safer for the breast than the older synthetic progestogens. Vaginal oestrogen for genitourinary symptoms is safe for almost everyone and can be used long-term. Testosterone, off-licence in the UK but supported by the British Menopause Society, has a place for low sexual desire that persists on HRT.

I do not position myself as your HRT prescriber. That decision belongs with you and your GP or a menopause specialist, and it should be made with your full history in front of them. What I do is the rest of it, and I will write to your GP with what I have found so that the HRT decision is made with the whole picture.

The rest of it is where much of the difference lies for the women who come to me on HRT and still not well. In rough order of how often it matters:

1. Sleep. Nothing else works well while sleep is broken. Vasomotor symptoms disrupting sleep are the clearest indication for HRT, but apnoea, alcohol, late eating and an evening of screens are frequently doing as much damage.
2. Iron, thyroid and vitamin D, corrected properly rather than nudged.
3. Insulin sensitivity. Protein at every meal, resistance training two or three times a week, fewer refined carbohydrates, and a modest overnight fasting window. This is the intervention with the widest benefit: weight, energy, mood, cholesterol and long-term brain health.
4. Alcohol. It worsens flushes, sleep, mood and breast cancer risk, and tolerance falls in this decade. I am not going to lecture you, but I will be honest about it.
5. Strength. Muscle and bone both decline faster after menopause, and resistance training is the only intervention that reliably slows both. It also improves insulin sensitivity and mood.
6. Targeted supplementation where a deficiency was found, and a small number of supplements with reasonable evidence for specific symptoms. I will tell you which have evidence and which are being sold to you.
7. Non-hormonal options for women who cannot or do not want to take HRT: CBT, certain antidepressants at low dose for flushes, and newer non-hormonal drugs acting on the brain’s temperature control, which your GP or specialist can discuss.

The cognitive and long-term angle

My main clinical work is in cognitive decline and the Bredesen Protocol, and it shapes how I see this decade. Two-thirds of people with Alzheimer's disease are women, and that is not fully explained by women living longer. The loss of oestrogen at menopause changes brain energy metabolism, and the years around it are a window in which vascular risk, insulin resistance, sleep and inflammation are all shifting at once.

The evidence on whether HRT protects the brain is genuinely mixed and depends heavily on timing: started around the menopause it appears neutral or possibly protective; started many years later it may be harmful. I will not overstate it. What I will say is that a woman in her late forties with brain fog, poor sleep, rising insulin and a parent with dementia has a set of modifiable risks that deserve attention now, whatever she decides about HRT, and that the brain fog itself almost always improves when the rest is dealt with.

Where there is a family history and the worry is real, I extend the assessment along the lines set out in the early Alzheimer's guide.

Who this suits

This assessment is a good fit if you are:

• In your forties or fifties with symptoms that have been attributed to stress, or that have not been explained
• On HRT, and better, but not well
• Unable or unwilling to take HRT and wanting a serious plan that is not just endurance
• Worried about brain fog or memory, particularly with a family history of dementia
• Told your bloods are normal, when nobody has looked beyond the basics
• Wanting one longer appointment with a doctor who will look at the whole picture and write it down

It is a poor fit if you want a hormone panel to confirm a diagnosis, a supplement protocol in place of HRT, or a practitioner who will tell you that HRT is dangerous. I will not do any of those.

Perimenopause and hormonal health are assessed under my functional medicine service. The initial consultation is two hours; fees and what is included are on the fees page. Testing is additional and I give a written estimate before anything is ordered. I see patients in Twickenham and Richmond, and online across the UK, and a discovery call costs nothing.