Hair Loss — Four Diseases That Look Alike

Hair loss is not a diagnosis. It is a symptom shared by conditions that have almost nothing in common — a hormone-driven miniaturisation, a synchronised shedding event, an autoimmune attack, and simple mechanical damage. One of them resolves on its own, two are treatable, and a fourth category destroys the follicle permanently.

One Complaint, Several Conditions

The sentence patients arrive with is the same regardless of what they have. Hair is coming out, the scalp is showing, the ponytail is thinner. What separates the conditions is not the complaint but the pattern, the timeline and what is happening at the level of the follicle.

Androgenetic alopecia thins hair without necessarily shedding much of it. Telogen effluvium sheds copiously while the remaining hair keeps its calibre. Alopecia areata removes hair in discrete patches over days. Traction alopecia removes it wherever tension has been applied, usually at the margins. Four mechanisms, four distributions, four prognoses.

Because the treatments do not overlap, the cost of guessing is measured in months rather than money. A patient treated for pattern loss who actually had a shedding event spends half a year on therapy for a condition that was going to settle anyway. A patient with an early scarring alopecia treated as pattern loss spends the same half-year losing follicles that could not be recovered. The reasoning behind hair restoration begins with this separation rather than with a device.

The Question That Comes First

Before anything else, the examination establishes whether the alopecia is scarring or non-scarring. This is not a refinement of the diagnosis — it is the diagnosis, because it determines whether regrowth is biologically possible at all.

In non-scarring alopecia the follicle is still present. It may be miniaturised, resting, or under immune attack, but the stem cell population in the bulge region survives and the follicular ostia — the visible pores from which hairs emerge — are still there on the scalp surface. Anything that removes the insult, or supports the follicle, has something to work with.

In scarring alopecia the follicular unit has been destroyed and replaced by fibrous tissue. The ostia disappear, the scalp surface becomes smooth and shiny, and what remains is scar. No medication, laser, injection or growth factor regrows hair from a follicle that no longer exists. Scarring alopecias are dermatological conditions, frequently inflammatory, and they belong with a dermatologist promptly — the value of an early appointment is entirely in stopping the process before more follicles are lost.

Androgenetic Alopecia — Miniaturisation

The commonest by a wide margin. Susceptible follicles carry receptors sensitive to dihydrotestosterone, and under that influence each successive hair cycle produces a shorter, finer, less pigmented hair from a progressively smaller follicle. The follicle does not die suddenly. It shrinks over years.

The clinical signature is calibre variability. Examine the scalp closely and the affected area contains thick terminal hairs, intermediate hairs and fine vellus hairs side by side, because the follicles are at different stages of the same process. Uniform hair calibre across a thinning area argues against pattern loss and points elsewhere.

Distribution is patterned and predictable — temporal recession and vertex thinning in men, central widening with a preserved frontal hairline in women. It is progressive, it does not remit spontaneously, and treatment is maintenance rather than cure. The mechanism of androgenetic alopecia is the reason therapy is described in terms of holding ground rather than finishing a course.

Telogen Effluvium — Shedding, Not Thinning

Telogen effluvium is a cycling disorder rather than a follicular disease. A systemic insult pushes an abnormally large proportion of follicles out of the growth phase and into the resting phase simultaneously. Those hairs are shed together roughly three months later, when the follicles re-enter growth and push the old shafts out.

The presentation is alarming and distinctive — handfuls in the shower, hair on the pillow, shedding that patients can quantify because it is so far outside their normal. Yet the hair that remains is of normal calibre, the distribution is diffuse rather than patterned, and the scalp examination is otherwise unremarkable.

It is usually self-limiting. Once the trigger has passed, the follicles that shed are already regrowing, and the shedding stops within several months without intervention. The trigger almost always sits about three months before the shedding began, which is why the history matters more than any test — the timing of sudden hair shedding is itself the diagnostic finding.

Alopecia Areata — Discrete And Autoimmune

Alopecia areata is an immune-mediated attack on the anagen follicle. The immune privilege that normally protects the growing hair bulb collapses, lymphocytes surround it, and the follicle abruptly stops producing a shaft. The follicle itself survives, which is why regrowth remains possible even after long periods of loss.

The pattern is unmistakable when it is typical — one or more round or oval patches of complete loss, appearing over days, with a smooth scalp surface and preserved follicular ostia. Exclamation-mark hairs, short and tapered toward the scalp, may be visible at the active margin. It can also present diffusely, which is where it becomes easy to mistake for effluvium.

The course is unpredictable. Single patches frequently regrow spontaneously; extensive or recurrent disease behaves differently and belongs under dermatological management. It is not a cosmetic condition and is not treated as one — alopecia areata is identified at the examination and referred where the extent warrants it.

Traction Alopecia — Mechanical And Avoidable

The fourth is not a disease of the follicle at all. Sustained mechanical tension — tight ponytails, braids, buns, extensions, weaves, religious or occupational head coverings worn tightly, and long-term clip placement in the same spot — pulls the follicle repeatedly and eventually damages it.

Its distribution follows the tension rather than any biological pattern, which makes it recognisable. Loss concentrates at the frontal and temporal margins, or in a line along a parting, or wherever the style loads the hair. The fringe sign — a band of retained short fine hairs at the very front edge with loss immediately behind it — is characteristic.

Early traction alopecia is entirely reversible because the follicle is only inflamed and stressed. Sustained traction eventually produces perifollicular fibrosis, and at that point the condition has become a scarring alopecia and the loss is permanent. This is the one form of hair loss a patient can stop by changing behaviour, and the reason traction alopecia carries the strongest argument for an early appointment of anything on this list.

What The Examination Actually Involves

History first, because it does most of the work. Onset and speed, whether the complaint is shedding or thinning, family pattern, medications, recent illness or surgery, pregnancy and postpartum timing, weight change and dieting, and styling habits over years rather than months. A shedding event dated to three months after a documented trigger is largely diagnosed before the scalp is touched.

Then examination of the scalp surface under magnification. Follicular ostia are looked for specifically — present or absent decides scarring from non-scarring. Hair calibre variability is assessed to identify miniaturisation. Perifollicular erythema and scale are noted, because both suggest an inflammatory process rather than a hormonal one. A gentle pull test estimates active shedding.

Blood work is directed rather than reflexive — iron studies and thyroid function where the history suggests them, particularly in women with diffuse loss. What follows depends entirely on which of the four conditions the examination has identified, and whether medical therapy is appropriate at all is a conclusion of that process rather than an assumption preceding it.