What is perimenopause and menopause?
Menopause is defined as the permanent cessation of menstrual periods, confirmed after 12 consecutive months without a period. The average age at menopause in the United States is 51, though the range is typically 45–55. What most people don't realise is that the journey to menopause — the perimenopausal transition — can begin 8–10 years earlier, often in the early to mid-40s and sometimes in the late 30s. During this transition, the ovaries' follicular reserve is declining, and the hormonal signals that have governed the menstrual cycle for decades begin to shift. This is not a sudden drop; it is a complex, dynamic fluctuation.
The hormone cascade of perimenopause follows a specific sequence. Progesterone declines first, typically beginning in the late 30s as ovulation becomes less consistent. Without ovulation, the corpus luteum doesn't form, and progesterone output falls. Estrogen, by contrast, does not simply decline — it fluctuates erratically, with both supraphysiological spikes and crashes, before eventually trending downward as the follicular reserve depletes. Meanwhile, FSH (follicle-stimulating hormone) and LH (luteinising hormone) rise as the pituitary attempts to drive ovulation from declining-quality follicles. This hormonal turbulence — not a simple linear decline — is responsible for the wide variety and unpredictability of perimenopausal symptoms.
True menopause is characterised by sustained low estrogen and progesterone alongside elevated FSH (typically above 30–40 mIU/mL). The post-menopausal years bring their own physiology, with new cardiovascular, metabolic, cognitive, and skeletal considerations that deserve proactive management rather than passive acceptance.
Why functional medicine matters here: Conventional medicine typically addresses menopause with a decision: hormones or no hormones. Functional medicine asks a different set of questions first: How are your adrenals — the backup estrogen production site post-menopause? How is your gut microbiome managing estrogen metabolism? What is your thyroid doing? How is your sleep and stress load affecting this transition? These factors determine whether you experience menopause as a manageable transition or a decade of suffering. Getting them right changes the outcome dramatically.
Common symptoms of perimenopause and menopause
- Hot flashes (vasomotor symptoms) — Sudden, intense waves of heat, typically starting in the chest and radiating to the face and neck, lasting 1–5 minutes. Caused by narrowed thermoregulatory zones in the hypothalamus as estrogen fluctuates. Occur in approximately 75% of menopausal women and can persist for 7+ years.
- Night sweats — Hot flashes occurring during sleep, often soaking nightwear and bedding, causing fragmented sleep and next-day fatigue. Among the most disruptive symptoms for quality of life.
- Sleep disruption — Multi-factorial: night sweats, reduced progesterone (which has GABAergic sedative properties), elevated cortisol from HPA axis changes, and altered circadian rhythms all contribute. Poor sleep compounds every other symptom.
- Mood changes, depression, and anxiety — Estrogen modulates serotonin, dopamine, and norepinephrine signalling. Fluctuating estrogen disrupts neurotransmitter balance, producing irritability, low mood, new-onset anxiety, and in some women, frank depression. Perimenopause is a recognised window of vulnerability for depression.
- Brain fog and cognitive changes — Difficulty with word retrieval, concentration, and short-term memory are among the most distressing and least discussed perimenopausal symptoms. Estrogen is neuroprotective and supports synaptic plasticity and cerebral blood flow.
- Joint pain and stiffness — Estrogen has significant anti-inflammatory properties and supports joint lubrication. Its decline is associated with increased joint pain, particularly in the hands, knees, and hips. Often misattributed to ageing.
- Genitourinary syndrome of menopause (GSM) — Vaginal dryness, atrophy, reduced lubrication, and urinary urgency, frequency, and recurrent UTIs caused by the loss of estrogen's trophic effect on urogenital tissues.
- Low libido — Driven by declining testosterone (produced in the ovaries and adrenals), vaginal discomfort making intercourse painful, mood changes, and sleep deprivation.
- Hair thinning and skin changes — Estrogen and progesterone support hair follicle cycling and collagen synthesis. Their decline leads to increased hair shedding, finer hair texture, and accelerated skin thinning and laxity.
- Weight redistribution — Metabolic changes in menopause favour central adiposity (abdominal fat) even without caloric changes. Insulin sensitivity decreases, and the body composition shifts toward higher fat, lower lean mass.
- Heart palpitations — Estrogen receptors are present in cardiac tissue; estrogen withdrawal can cause arrhythmias and palpitations in the absence of cardiac disease. These require proper evaluation to rule out structural causes but are frequently benign and hormone-related.
Why conventional medicine undersupports women in perimenopause
The 2002 Women's Health Initiative (WHI) study profoundly shaped conventional medicine's approach to menopause for two decades. The study reported increased risks of breast cancer, cardiovascular disease, stroke, and blood clots in women taking combined synthetic hormone therapy (conjugated equine estrogen + medroxyprogesterone acetate). The medical establishment's response was to broadly discourage hormone therapy, leaving millions of women without effective treatment for significant symptoms.
The WHI's findings have since been substantially reanalysed and contextualised. The study used older women (average age 63, well past menopause), synthetic non-human estrogen, and a synthetic progestogen that behaves differently from natural progesterone. More recent analyses, including the data-driven work of the Menopause Society (formerly NAMS), support that for healthy women under 60 or within 10 years of menopause, the benefits of hormone therapy outweigh the risks — particularly when bioidentical hormones are used, and estrogen is delivered transdermally (avoiding first-pass liver metabolism and the associated clotting risks of oral estrogen).
How functional medicine approaches menopause and perimenopause
Functional medicine begins the menopause conversation in perimenopause — often years before conventional medicine engages. Practitioners use comprehensive hormone testing (including progesterone, all estrogen fractions, testosterone, DHEA-S, SHBG, FSH, LH, and cortisol) to understand the full hormonal picture at that moment, then track it as the transition unfolds.
Root causes they look for
- Progesterone decline as the first domino — Identifying and addressing early progesterone deficiency through targeted supplementation (natural progesterone, not synthetic progestins) before estrogen fluctuations become the dominant feature.
- Cortisol-sex hormone competition — The adrenal glands are the body's backup estrogen and testosterone production site after menopause. Chronic stress depletes the adrenal reserve needed for this transition, worsening symptoms significantly. Adrenal support is fundamental to menopause care.
- Thyroid intersection — Hypothyroidism and Hashimoto's thyroiditis frequently emerge or worsen in perimenopause, with overlapping symptoms (fatigue, weight gain, brain fog, mood changes) that can mask or mimic menopausal symptoms. Comprehensive thyroid assessment is essential.
- The gut-estrogen axis (estrobolome) — A collection of gut bacteria called the estrobolome produces an enzyme (beta-glucuronidase) that metabolises estrogen conjugates in the intestine, determining whether estrogen is reabsorbed or excreted. Dysbiosis disrupts estrogen metabolism, contributing to both estrogen dominance and inappropriate estrogen clearance. Supporting the estrobolome through dietary fibre, probiotic foods, and treating dysbiosis improves hormonal balance and reduces vasomotor symptoms.
- Nutrient deficiencies — Magnesium (critical for sleep and progesterone function), vitamin D (anti-inflammatory, bone protective), omega-3 fatty acids (vasomotor symptom reduction, mood support), B vitamins (methylation and estrogen metabolism), and calcium are commonly deficient.
Treatment approaches
The functional medicine approach to menopause is individualised, with treatment decisions guided by the patient's symptom severity, testing results, personal risk profile, and preferences.
- Bioidentical hormone replacement therapy (BHRT) — Hormones with molecular structures identical to those produced by the human body (17-beta estradiol, progesterone, testosterone). Delivered transdermally (patches, gels, creams) or vaginally to minimise systemic risks. Evidence supports significant symptom relief, bone density preservation, cardiovascular protection when initiated early in the transition, and potential cognitive benefit.
- Dietary support — High fibre intake (supports estrobolome and estrogen clearance), phytoestrogen-rich foods (flaxseed, legumes, fermented soy) shown to modestly reduce vasomotor symptoms, cruciferous vegetables (DIM supports estrogen metabolism through beneficial pathways), and reduction of ultra-processed foods that disrupt blood sugar and amplify hormonal instability.
- Targeted supplementation — Magnesium glycinate (sleep, mood, bone), vitamin D3 + K2 (bone density, immune function), omega-3 EPA/DHA (vasomotor symptoms, cardiovascular risk), DIM (diindolylmethane, supports 2-hydroxy estrogen metabolism), and black cohosh (evidence-supported reduction of hot flash frequency).
- Adrenal support — Adaptogenic herbs, cortisol management, sleep optimisation, and stress reduction to maximise the adrenal reserve that becomes critical for post-menopausal hormone production.
- Gut microbiome work — Testing and treating dysbiosis, SIBO, or candida overgrowth to restore healthy estrobolome function; increasing dietary fibre and fermented foods; targeted probiotic supplementation.
- Sleep optimisation — Addressing night sweats (hormone therapy if appropriate, magnesium, progesterone), sleep hygiene, circadian rhythm support, and in some cases CBT-I (cognitive behavioural therapy for insomnia).
- Exercise prescription — Resistance training is particularly important for preserving lean mass, bone density, and insulin sensitivity; Zone 2 cardiovascular work supports metabolic health; yoga and breath-work reduce cortisol and vasomotor symptoms.
What to look for in a menopause specialist
- Treats perimenopause, not just menopause — A practitioner who engages with the transition from the start, not only after periods have stopped.
- Experienced with BHRT — Knowledgeable about bioidentical options, transdermal delivery, and the current evidence base, including the updated risk-benefit profile post-WHI reanalysis.
- Assesses the full hormonal picture — Testing estradiol, progesterone, testosterone, DHEA-S, SHBG, FSH, LH, thyroid panel, and cortisol together.
- Understands the estrobolome — Addresses gut microbiome health as part of hormonal support, not an afterthought.
- Integrates adrenal and thyroid assessment — Recognising the interconnectedness of the stress-thyroid-sex hormone axis.
- Respects patient autonomy on HRT decisions — Provides balanced, evidence-based information about risks and benefits rather than reflexively recommending for or against hormone therapy.
