What’s actually going on
How I think about this.
Hair loss in adults is commonly a downstream signal. The follicle is one of the most metabolically demanding structures in the body, and it shuts down first when the system is short on what it needs. The drivers I see most are thyroid drift (subclinical hypothyroid commonly presents with hair changes first), iron and ferritin gaps (women in particular run ferritin too low to support healthy hair even when their hemoglobin is normal), hormonal shifts in perimenopause and andropause, protein insufficiency in patients who think they are eating enough but aren’t, and the inflammation patterns that come out of gut dysbiosis.
For male-pattern hair loss, DHT sensitivity at the scalp is the proximate cause, but the upstream metabolic and hormonal context shapes how aggressively it progresses. For female-pattern hair loss, the DHT pathway matters less and the estrogen, progesterone, and thyroid story matter more.
Stress-driven hair loss (telogen effluvium) typically shows up two to three months after the stressor, which makes patients miss the connection entirely.
Before anything else
When hair loss needs medical evaluation.
Everything further down this page is about physiology that can contribute to this symptom. None of it replaces a conventional diagnosis, and some presentations need to be seen rather than measured. Start here.
See a physician promptly, within days
- Patches of complete hair loss with smooth skin, or loss of eyebrows and eyelashes
- Redness, scaling, scarring or pain on the scalp. Scarring alopecias destroy follicles permanently and need dermatology quickly, because what is lost does not return
- Rapid hair loss with new facial hair, voice deepening or irregular periods
- Hair loss alongside weight loss, fever or a new rash
Worth a routine medical evaluation
- Shedding that has continued for more than six months
- Gradual thinning in a recognisable pattern
- Hair loss following a pregnancy, illness or crash diet, which is usually self-limiting but worth confirming
Diffuse shedding with a healthy scalp and no scarring is exactly the situation where iron, thyroid and nutrient status are worth measuring properly.
This list covers the presentations that most often need conventional assessment. It is not exhaustive, and it does not replace clinical judgement. If something feels wrong and is not on it, that is still a reason to be seen.
Systems that can contribute
Where hair loss can come from.
Each of these can be part of the picture. None of them is the answer on its own, and finding something here does not establish that it is the reason you feel the way you do.
Iron status
Ferritin is the single most useful measurement in diffuse hair shedding, and it can sit inside the reference range while still being too low for the follicle.
Thyroid physiology
Both underactive and overactive thyroid cause diffuse shedding.
Androgen signalling
Pattern hair loss is driven by follicle sensitivity to androgens rather than by high androgen levels, which is why levels are often normal.
Nutritional status
Protein intake, zinc and vitamin D can each contribute, and rapid weight loss is a common trigger.
The hair cycle and stressors
Telogen effluvium follows a stressor, illness, childbirth or surgery by roughly three months, which is why the trigger is often forgotten by the time the shedding starts.
Medication effects
Several classes cause shedding, usually reversibly.
The physician’s lens
How I read this in practice.
I read hair loss with the full thyroid panel (TSH alone is not enough), iron studies with ferritin (target above 70 ng/mL for hair, not the lab’s floor of 15), the sex hormones with binding proteins, fasting insulin, vitamin D, omega-3 index, and zinc status. The metabolomic panel catches the nutrient story underneath all of this. For sudden shedding, I look back three months for what changed.
The systems behind it
Where this symptom comes from.
Most cases touch more than one. Open each area to read the biology underneath.
Biological pillars
Pillar
Metabolism & Metabolomics.
Urinary organic acids read the upstream patterns of energy production, neurotransmitter balance, detoxification, and recovery.
Read this pillarPillar
Gut-Immune Health.
The gut microbiome interacts extensively with immune, metabolic, and gastrointestinal physiology. Read the ecosystem as one system.
Read this pillarPillar
Exposomics.
The cumulative environmental load a person carries can matter for physiology. Some of it can be measured, and I assess it when your history says it is relevant.
Read this pillar
What measurement settles
What testing can and cannot tell you here.
Testing can help identify
- Measure ferritin, full iron studies, thyroid function, vitamin D and zinc
- Identify the androgen and metabolic context in pattern hair loss
Testing cannot by itself establish
- Diagnose the type of hair loss, which requires examination of the scalp and sometimes a biopsy
- Detect scarring alopecia, which is a clinical and histological diagnosis and is time-critical
- Predict whether hair will regrow
What may help clarify it
The data that explains it.
Hair work needs the thyroid axis read properly (TSH with free T3, free T4, reverse T3), iron studies with ferritin, and the sex hormones together. The metabolomic panel adds the nutrient and detoxification patterns standard labs miss.
What I would measure
The hormone network, measured together
Reads the full thyroid axis, sex hormones, and ferritin together. The three most common drivers of hair loss in one draw.
Explore working with Dr. TaggeWhat I would measure
Cellular and metabolic markers
Adds B-vitamin status, methylation, zinc, and the toxic-metal load that can disrupt follicle metabolism.
Explore working with Dr. Tagge
While you wait
Moves worth making before testing.
These are the levers I’d pull while we set up the workup. Most of them produce real signal inside two weeks.
- Eat 30 grams of protein at breakfast. Most hair-loss patients are underfeeding their follicles before lunch.
- Get your ferritin checked. Optimal for hair is above 70 ng/mL, not the lab’s normal floor of 15.
- Cut crash diets and aggressive caloric deficits. Hair shuts down first when the body senses a famine.
- If you recently went through a big stressor (illness, surgery, childbirth, big life event), expect the shedding three months later. The cause is real even when it does not feel related.
If two weeks of the basics doesn’t move the needle, that is the kind of presentation a call with me exists for. Your biology is telling you something the lifestyle layer cannot fix on its own.
Your next step
Measure it, then decide.
There is a coherent measurement pathway here. What a panel does not include is someone reading it against your history, and that reading is where care with me begins.
What to read next
Go one level deeper.
- How I think
- The framework: how a symptom, a result and a history are read together, and why a reference range is not the same as a person’s range.
- The systems
- Metabolism & Metabolomics · Gut-Immune Health · Exposomics
- Terms used here
- Detoxification · Dysbiosis · Fasting insulin · Ferritin · Omega-3 index · Reference range
Essays on this
Essay
A ferritin of 20: what a "normal" result can miss.
Ferritin answers a different question from hemoglobin. Iron stores can run down before anemia appears, and inflammation can make a ferritin look reassuring when it is not. The work is deciding whether iron deficiency is present, why it developed, whether it explains the symptoms, and whether the response to treatment confirms it.
Read thisEssay
EMF exposure and health: the honest answer.
The EMF discourse oscillates between dismissal and catastrophe. The honest position is that the evidence for harm at typical exposure levels is weak, the harm-mitigating habits are cheap, and one specific exposure (phone in the bedroom) is worth addressing for reasons beyond EMF.
Read thisEssay
What is the exposome? And why I read it.
Your exposome is the cumulative environmental load your body has carried over a lifetime. Most of it is measurable. Most of it is reducible. And most of the time it is the missing piece on a plan that is not working.
Read this
Browse other symptoms
Something else on your mind?
Fatigue and low energy
When the tank stays low no matter how much you sleep.
Brain fog
The lights are on but the signal feels weak.
Poor sleep
Either you can’t fall asleep, or you can’t stay asleep.
Perimenopause
The years when the body’s hormonal rhythm changes, before the period stops.
Low libido
Desire that used to be reliable is gone or muted. Both sexes, both directions.
Hair loss
Thinning, shedding, or texture changes that didn’t used to happen.
Erectile dysfunction
ED is the canary. The body is telling you something about vascular and hormonal health.
High cholesterol concern
Your last lab flagged it. You want a second opinion before you take a statin.
High blood pressure concern
The reading came back elevated. You want the full picture before you start a prescription.
Food cravings
Cravings are biology pulling for what it needs, disguised as whatever is easiest to grab.
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