When Hair Loss Isn't Genetic: Thyroid, Medication and Medical Causes

Most hair loss in men, and a good deal in women, is pattern hair loss driven by inherited sensitivity to a normal hormone. But not all of it is, and the causes that are not behave differently, respond differently, and in several cases resolve entirely once the underlying issue is addressed.

This matters practically. A hair transplant is not an appropriate response to hair loss caused by an untreated thyroid condition or an iron deficiency. Establishing the cause comes first.

Why the cause is assessed before anything else

Three reasons.

Some causes are reversible. Correcting them restores hair without any intervention on the scalp.

Some causes make surgery inadvisable. Transplanting into an actively inflamed or progressively scarring scalp has a poor prognosis.

And some causes are markers of something worth knowing about for reasons beyond your hair.

At consultation, Dr Daood examines the pattern and character of the loss, takes a history, and where the presentation does not fit pattern hair loss, will direct you back to your GP for investigation before discussing surgery.

Telogen effluvium

The most common non-genetic cause, and the one most often misread.

A significant physiological stressor pushes a large proportion of follicles into the resting phase at once. Because that phase lasts a few months, the shed appears two to three months after the event, by which time the trigger has often been forgotten.

Common triggers: major illness, high fever, surgery, general anaesthetic, childbirth, rapid or substantial weight loss, crash dieting, and severe psychological stress.

The presentation is diffuse. Hair comes out from across the scalp rather than in a pattern, the hairs shed are full-length and normal in calibre, and the hairline does not move.

It recovers. Follicles pushed into telogen re-enter the growth phase and density returns, though because hair grows at roughly a centimetre a month, visible recovery takes some months.

What makes it confusing is that a telogen shed often reveals underlying pattern loss that was already present but unnoticed. The shed resolves. What it exposed does not.

Thyroid dysfunction

Both underactive and overactive thyroid commonly affect hair.

Hypothyroidism is associated with hair that becomes dry, coarse and brittle, along with diffuse thinning. Loss of the outer third of the eyebrows is a recognised though not universal sign.

Hyperthyroidism more often produces fine, soft hair with diffuse thinning.

The loss is generally diffuse rather than patterned, and it tends to improve once thyroid function is corrected, though improvement lags the treatment by months.

Thyroid function is a simple blood test and worth doing if diffuse shedding persists, particularly alongside fatigue, weight change, temperature intolerance or changes in mood or bowel habit.

Iron deficiency

Iron is required for the rapid cell division that anagen follicles depend on, and deficiency is a common contributor to diffuse shedding, particularly in women of reproductive age.

The relevant measure is usually ferritin, which reflects iron stores, rather than haemoglobin alone. It is possible to have normal haemoglobin and depleted ferritin, and to be shedding as a result.

Correcting a genuine deficiency helps. Supplementing when levels are normal does not, and excess iron carries its own risks. This is a question for bloods and your GP rather than guesswork.

See diet and hair health.

Other nutritional factors

Protein. Hair is largely keratin. Sustained inadequate protein intake affects hair, though this requires genuine deficiency rather than eating slightly less than optimal.

Zinc. Deficiency is associated with hair loss. Uncommon on a varied diet.

Vitamin D. Low levels are associated with several forms of hair loss, though whether correcting them improves hair is less well established.

Vitamin A in excess. Notable because this is one where too much, rather than too little, causes shedding. Generally arises from supplementation or retinoid medication rather than diet, and it reverses on stopping.

Biotin. Widely marketed for hair. Genuine biotin deficiency is rare, and there is little evidence that supplementing in the absence of deficiency achieves anything.

Medications

A range of medications can cause hair shedding. This is not an exhaustive list, and the fact that a medication can cause shedding does not mean it will in any individual.

Categories reported to affect hair include some anticoagulants, some antidepressants, beta blockers, retinoids, certain anticonvulsants, some medications used for gout, high-dose vitamin A derivatives, and hormonal medication including some contraceptives.

Chemotherapy agents cause abrupt loss by a different mechanism, targeting rapidly dividing cells including anagen follicles. This is largely reversible once treatment ends, although regrowth can differ in texture or colour.

Do not stop any prescribed medication because of hair loss. Raise it with the prescribing doctor. In many cases the medication is more important than the hair, and in some cases an alternative exists.

Alopecia areata

An autoimmune condition in which the immune system attacks hair follicles, producing discrete circular patches of complete loss rather than diffuse thinning or a recognisable pattern.

It can affect the scalp, beard, eyebrows or elsewhere. Course is unpredictable. Some episodes resolve spontaneously, some recur, and a minority progress more extensively.

It is not pattern hair loss and it is not treated surgically. Transplanting into an area affected by active alopecia areata is inappropriate, since the immune process would affect the transplanted follicles too.

Traction alopecia

Caused by sustained mechanical tension on the follicle from tight hairstyles.

Early on it is reversible once the tension is removed. If tension continues long enough, the follicle scars and the loss becomes permanent. At that point surgery may be appropriate, provided the causative styling has stopped.

Covered in full in traction alopecia.

Scarring alopecias

A group of conditions in which inflammation destroys the follicle and replaces it with scar tissue. Frontal fibrosing alopecia and lichen planopilaris are examples.

These require dermatological diagnosis and management. The critical point for surgery is that the condition must be stable and inactive before any transplant is contemplated, because operating into an active scarring process risks losing the grafts to the same mechanism.

Female pattern hair loss

Worth mentioning here because it is frequently mistaken for a non-genetic cause.

Female pattern loss typically presents as diffuse thinning across the top of the scalp and widening of the part rather than the recession and crown loss seen in men. Because it looks diffuse, it is often assumed to be a deficiency or a thyroid problem.

It can be either, or both at once, which is why investigation matters before concluding anything.

See female hair transplants and women's hair loss.

What to investigate, and with whom

Your GP is the right starting point for anything that does not present as clear pattern hair loss.

Reasonable initial investigations, depending on the presentation: full blood count, ferritin and iron studies, thyroid function, and vitamin D. Depending on findings and history, hormonal assessment may be relevant, particularly in women.

Where the presentation suggests a scalp condition rather than a systemic cause, dermatological referral is appropriate.

When to consider surgery

Surgery is appropriate for hair loss that is patterned, stable, and where the follicles have been genuinely lost rather than temporarily disrupted.

It is not appropriate where a reversible cause has not been addressed, where a scarring condition is active, where the loss is diffuse and unpatterned including the donor area, or where the diagnosis is unclear.

See are you a suitable candidate.

Getting assessed

Dr Jassim Daood has practised for over 30 years and performs both FUE and FUT surgery at our Bankstown clinic. Where the presentation suggests a cause other than pattern hair loss, he will say so and direct you to appropriate investigation rather than proceeding.

A GP referral is required before a cosmetic surgery consultation. Read our risks and complications page before considering surgery.

Get in touch.

Related reading: how much hair loss is normal, seasonal hair loss, male pattern baldness and the Norwood Scale.