Terms explained

Glossary: hair loss and hair transplantation from A to Z

Here you will find the most important terms in hair loss and hair transplantation explained in plain language. Use the glossary as a reference work when you come across a technical term in a consultation or in a clinic's description.

5-alpha-reductase: The enzyme that converts testosterone into DHT. This is the enzyme that Finasteride and Dutasteride block.
5-alpha-reductase inhibitor: The drug class that blocks conversion of testosterone into DHT. Finasteride and dutasteride are the two used for hair loss.
Afro-textured hair: Tightly curled hair whose follicle curves beneath the skin. The curve makes extraction harder and raises transection risk, so it calls for adapted punch technique and an experienced team.
Aftercare protocol: The written instructions a clinic gives for washing, sleeping, activity and medication after surgery. A clinic that provides none in writing is a warning sign in itself.
All-inclusive package: A quoted price bundling surgery, hotel, transfers and translation. What matters is which of graft count, technique, medication and follow-up are inside the figure and which are charged later.
Alopecia: The medical umbrella term for hair loss, whatever the cause. There are many forms, and the treatment depends entirely on the type.
Alopecia areata: An autoimmune condition in which the immune system attacks the follicles and produces round, sharply defined bald patches.
Alopecia totalis: A form of alopecia areata in which all scalp hair is lost. It is an autoimmune condition, not hereditary hair loss, and is not treated with transplantation while active.
Alopecia universalis: The most extensive form of alopecia areata, with loss of hair on the scalp and the rest of the body.
Anagen: The growth phase of the hair, lasting 2 to 7 years. Normally 85 to 90 percent of the hairs are in anagen at the same time.
Androgen: A group of hormones, including testosterone and DHT, that drive male characteristics. In genetically susceptible follicles, androgens are what trigger the miniaturisation behind pattern hair loss.
Androgen receptor: The protein inside a cell that DHT binds to. Sensitivity of this receptor is inherited and is a large part of why two people with similar hormone levels can lose very different amounts of hair.
Androgenetic alopecia: Hereditary hair loss driven by the hormone DHT. The most common cause of permanent hair loss in both men and women.
Antiandrogen: A medication that reduces androgen activity. Spironolactone and cyproterone acetate are used for female pattern hair loss in some countries, under medical supervision.
Arrector pili muscle: The small muscle attached to each follicle that raises the hair. It is one of the structures a follicular unit graft may carry with it.
ARTAS: A robotic system that assists FUE extraction by locating and punching follicular units. It automates part of the harvest; planning, site creation and placement remain human decisions.
ATA (atmospheres absolute): The unit of pressure used to describe a hyperbaric session. Ambient air is 1 ATA; hyperbaric protocols run above that.
ATP (adenosine triphosphate): The molecule cells use to carry energy. Some graft preservation solutions add it on the reasoning that stored follicles continue to need an energy supply.
Beard grafts: Follicles taken from the beard as an additional donor source when scalp donor supply is limited. The hair is coarser and grows differently, so it is usually placed where that texture is least visible.
Beard transplantation: Transplanting scalp follicles into the beard area to add density or fill patches. Planning differs from the scalp because beard hair grows at a much shallower angle.
Biotin: A B vitamin widely marketed for hair. Deficiency is uncommon in people eating a balanced diet, and evidence that supplementing beyond normal levels improves growth is limited. High doses can also interfere with some laboratory blood tests.
Blood supply (recipient area): The vascular network that must reach a newly placed graft for it to survive. It is the practical limit on how densely grafts can be packed.
Blood test panel (hair loss): The set of tests commonly used to look for correctable contributors to hair loss, typically including ferritin, thyroid function and vitamin D. It identifies causes that treatment can address rather than diagnosing hereditary loss.
Body hair transplantation (BHT): Using hair from the chest, back or limbs as a supplementary donor source. Growth rates and cycle lengths differ from scalp hair, so results are less predictable and it is normally a secondary option.
Bulb: The widened base of the follicle, containing the cells that divide to produce the hair shaft. Damage to the bulb during extraction is one reason a graft may fail.
Catagen: A short transitional phase of 2 to 3 weeks in which the follicle contracts and growth stops.
CCCA (central centrifugal cicatricial alopecia): A scarring alopecia that begins at the crown and spreads outward, most often reported in women of African descent. Because it destroys the follicle, transplantation is only considered once the condition is confirmed inactive.
CE marking: A declaration that a device meets EU regulatory requirements. It concerns the equipment, not the skill of whoever uses it, and is not a quality award.
Choi implanter: The hollow pen-shaped instrument used in DHI, which holds a graft and places it into the scalp in a single action, making the site and inserting the hair at once.
Cicatricial alopecia: The medical term for scarring alopecia: hair loss in which the follicle is replaced by scar tissue and cannot regrow. Distinguishing it from non-scarring loss changes the whole treatment plan.
CNS (central nervous system): The brain and spinal cord. It appears in discussions of systemic side effects of hair-loss medication.
Consultation (in person vs photo): An assessment made by examining the scalp directly, versus one made from submitted photographs. Photographs are a reasonable starting point but cannot measure miniaturisation or donor density the way trichoscopy can.
Crusting: The small scabs that form over recipient sites in the first days after surgery. They separate on their own over roughly one to two weeks.
Dense packing: Placing grafts at a high number per square centimetre. It can look fuller but raises demands on blood supply and technique, and carries a higher risk of poor survival if pushed too far.
Density (grafts per cm2): How many follicular units sit in a square centimetre. Native scalp is typically far denser than any transplant achieves, which is why a transplant redistributes hair rather than restoring original density.
Dermal papilla: The group of cells at the base of the follicle that governs the growth and cycle of the hair. Central to research into hair regeneration.
DHI: Direct Hair Implantation. A placement technique in which a Choi pen opens the channel and places the follicle in one step.
DHT (dihydrotestosterone): The hormone that miniaturises genetically sensitive follicles. It is formed from testosterone by the enzyme 5-alpha-reductase.
Diffuse thinning: Hair loss spread evenly across the scalp rather than following the familiar receding or crown pattern. It requires careful diagnosis, since the cause may be shedding, hereditary loss or a medical condition.
Donor area: The back and sides of the head, where the follicles are DHT-resistant. The hairs for a transplant are harvested from here. A limited lifetime resource.
Donor dominance: The principle that a relocated hair keeps its original properties in its new position. This is why transplanted hair is near-permanent.
DUPA (diffuse unpatterned alopecia): Hereditary hair loss that thins the whole scalp, including the donor area at the back and sides. Because the donor zone is not stable, a transplant is usually not advisable, which is why donor assessment matters before surgery.
Dutasteride: A more powerful DHT blocker that blocks both types of the enzyme. Often used off label when Finasteride is not enough.
Elasticity of the scalp: How far the scalp stretches. It affects donor planning, particularly for strip harvesting.
Exosomes: Cell-derived vesicles being investigated as a hair-loss treatment. They are not an approved therapy for hair loss, and the published evidence remains early-stage.
Extraction density: How many follicular units are taken per square centimetre of donor area. Taking too many too closely leaves the donor visibly thin, which is why a limit is set rather than maximised.
Eyebrow transplantation: Transplanting single-hair grafts into the eyebrow. Angle and direction are unusually demanding because eyebrow hair lies almost flat against the skin and changes direction across the brow.
FDA (US Food and Drug Administration): The United States regulator for medicines and devices. FDA approval applies to a specific product for a specific use, and is not a general endorsement of a treatment category.
Ferritin: The blood marker of stored iron. Low ferritin is a recognised and correctable contributor to shedding, particularly in women, which is why it is a standard test in a hair-loss workup.
Finasteride: A well documented DHT blocker in tablet form that slows hereditary hair loss by lowering DHT.
Follicular unit: The natural grouping of 1 to 4 follicles in which hair grows on the scalp.
Follicular unit excision: The current preferred name in the literature for FUE, describing extraction of individual follicular units with a punch rather than removal of a strip.
Folliculitis: Inflammation of the follicles, sometimes appearing as small spots in the recipient area during regrowth. It is usually mild and self-limiting, but persistent or painful cases need review.
Follow-up: Structured review after surgery, usually at intervals over the first year. Its absence is one of the most common gaps in low-cost packages.
FPHL (female pattern hair loss): The usual term for hereditary hair loss in women. It typically widens the parting and thins the top while preserving the frontal hairline, rather than producing the receding pattern common in men.
Freelance technicians: Whether the people performing extraction and placement are employed and consistent, or hired per case. Continuity of team is a reasonable proxy for consistency of result.
Frontal fibrosing alopecia: A scarring alopecia that moves the frontal hairline backwards in a band, most often in post-menopausal women, and often affects the eyebrows. It needs dermatological diagnosis, not surgery, while active.
FUE: Follicular Unit Extraction. The follicles are extracted one by one with a micro punch, leaving only small, dot shaped marks.
FUT: Follicular Unit Transplantation, also called the strip method. A strip of skin is removed and divided into grafts. It leaves a linear scar.
Graft: A transplanted follicular unit, that is a natural group of 1 to 4 hairs. The number of grafts is not the same as the number of hairs.
Graft count: A graft number set after examining the individual scalp, as opposed to a fixed package figure applied to every patient regardless of need.
Graft survival: The proportion of transplanted follicles that survive and grow. The true measure of the quality of a procedure.
Growth timeline: The expected sequence after surgery: shedding in the first weeks, early regrowth from around three to four months, and maturation of thickness and texture through to roughly twelve months or longer.
Hair calibre: The thickness of an individual hair shaft. Coarser hair covers more scalp per follicle, so two people with identical graft counts can end up with visibly different coverage.
Hair cycle: The repeating sequence each follicle runs through independently: anagen growth, catagen transition and telogen rest. Because follicles are out of step with one another, healthy scalps shed hair continuously rather than all at once.
Hair density: The number of hairs or follicular units per square centimetre. Naturally ideally over 50 follicles per cm2.
Hair follicle: The small structure in the skin that produces the hair shaft. If it is destroyed, it cannot be recreated.
Hair shaft: The visible part of the hair, made of dead keratinised cells. Its condition says nothing directly about the health of the follicle producing it.
Hair transplant repair: Corrective work on a previous transplant, such as removing or redirecting badly angled grafts, softening a hard hairline or camouflaging donor depletion. It is more constrained than a first procedure because donor supply has already been spent.
Hairline design: Deciding the position, shape and irregularity of the new hairline. It is the judgement that most determines whether a result looks natural, and a hairline set too low or too straight ages poorly.
HBOT (hyperbaric oxygen therapy): Breathing oxygen at greater than atmospheric pressure inside a chamber, studied as a way to support healing after surgery. Its role after hair transplantation is an area of active research rather than a settled standard.
Hypothermosol: A preservation solution designed to hold living tissue at low temperature, used in some clinics to store grafts. Its measurable advantage appears mainly over long storage times.
Implanter pen: The general term for the instrument used in DHI; the Choi implanter is the best-known type.
ISHRS: The International Society of Hair Restoration Surgery, the leading professional association for hair surgeons.
ISO certification: A standards certification covering organisational processes such as quality management. It says nothing directly about surgical outcomes.
JAK inhibitor: A drug class that suppresses part of the immune signalling pathway, approved in some countries for severe alopecia areata. It treats autoimmune hair loss, not hereditary hair loss.
Keratin: The structural protein that hair is made of. It is produced in the follicle, so applying it to the shaft cannot affect growth.
Ketoconazole shampoo: An antifungal shampoo used for seborrhoeic dermatitis and sometimes as an adjunct in hair loss. Evidence for a direct effect on hereditary loss is limited.
LDOM (low-dose oral minoxidil): Minoxidil taken as a tablet at low dose rather than applied to the scalp. It is prescribed off-label for hair loss in some countries and requires medical supervision, as it is a blood-pressure medication.
LLLP: The abbreviation used on this site for low-level laser treatment of the scalp, the same modality described in the literature as LLLT.
LLLT: Low level laser therapy with red light, which can mildly stimulate the follicles. Used as an add-on.
Medical tourism: Travelling abroad for treatment. It can lower cost substantially, and it also complicates follow-up, revision and recourse if something goes wrong.
Mega session: A single session transplanting a very large number of grafts, often above 3,000-4,000. Longer sessions increase time out of the body for the earliest grafts, which is a trade-off against fewer visits.
Microneedling: Treatment with fine needles that triggers a healing response and improves the absorption of Minoxidil.
Miniaturisation: The gradual process in which a follicle produces a thinner, shorter and lighter hair with every cycle, until it finally shuts down.
Minoxidil: A well documented topical or oral treatment that prolongs the growth phase of the hair and increases density.
MOH (Ministry of Health): The national health authority licence a clinic must hold to operate. It is a legal minimum rather than a mark of excellence.
Motorised punch: A rotating or oscillating punch used for FUE extraction. It is faster than a manual punch, and the trade-off is that it demands accurate depth and angle control to avoid transection.
No-shave FUE: FUE performed without shaving the recipient area, and sometimes only partially shaving the donor. It is more time-consuming and usually limits the number of grafts, but allows a patient to return to normal life immediately.
Norwood 3 vertex: A specific Norwood stage combining a receded frontal hairline with loss at the crown. It is one of the most common presentations at consultation.
Numbness: Reduced sensation in the donor or recipient area after surgery. It is common in the early weeks and usually resolves, though it can occasionally take months.
Occipital scalp: The area at the back of the head, and the core of the permanent donor zone.
Oedema: Swelling, typically of the forehead, in the first days after surgery. It is common, temporary and reduced by sleeping with the head elevated.
Off-label: Prescribing a licensed medicine for a use not covered by its official approval. It is legal and common, but it means the specific use has not been through the same regulatory review.
Out-of-body time: How long grafts spend outside the body between extraction and placement. Survival falls as this time lengthens, which is why session organisation matters as much as technique.
Package price: The common bundled offer for treatment in Turkey. Prices vary widely, and the meaningful comparison is what is included and who operates, not the headline figure.
Patients per day: How many operations a clinic runs in a day. High throughput and careful, evenly distributed extraction pull against each other.
PCOS (polycystic ovary syndrome): A hormonal condition that raises androgen levels and is a recognised cause of pattern hair loss in women. It is diagnosed and managed medically, and hair is only one of its features.
Pericytes: Cells wrapping small blood vessels, of interest in research into wound healing and follicle biology.
PFS (post-finasteride syndrome): A disputed condition in which symptoms are reported to persist after stopping finasteride. Case reports exist and some regulators have updated labelling, but causation, incidence and mechanism are not established.
Placement (graft insertion): Putting prepared grafts into the recipient sites. Handling here decides whether follicles are crushed or dried, and is one of the main determinants of survival.
Preservation solution: The fluid grafts are held in between extraction and placement. Options range from saline to solutions designed for organ preservation, and the difference shows mainly over longer storage times.
PRF (platelet-rich fibrin): A newer preparation derived from the patient's own blood, related to PRP but processed differently to produce a fibrin matrix. Evidence for hair loss is less mature than for PRP.
PRP: Platelet rich plasma. The growth factors from your own blood are injected into the scalp as a supportive treatment.
Punch diameter: The size of the cutting tool used to extract a follicular unit, usually between roughly 0.7 and 1.0 mm. A smaller punch leaves smaller donor marks but requires more precision to avoid cutting the follicle.
Recipient area: The thinning or bald area receiving the grafts.
Recipient channels: The small incisions opened in the recipient area, which determine the angle, direction and density of the hair. One of the most critical steps.
Recipient site: The small incision made to receive a graft. Its angle, direction, depth and density are decided before any graft goes in, and once made it cannot be changed.
Redness (erythema): Pinkness of the recipient area after surgery, which fades over weeks to months and is generally more visible and longer-lasting on lighter skin.
Revision surgery: A second procedure to correct or improve an earlier one, whether to add density, repair a hairline or camouflage scarring. It consumes donor supply that cannot be replaced.
Safe donor zone: The part of the donor area expected to remain near-permanent for life, defined conservatively because taking hair from outside it risks the transplanted hair thinning later.
Saline: A simple salt solution used to irrigate and hold grafts. It is designed for irrigation rather than for preserving living tissue, which is the argument for dedicated preservation solutions over long sessions.
Sapphire FUE: FUE in which the recipient channels are opened with sapphire blades instead of steel, which can produce more precise channels.
Scalp laxity: How loose or tight the scalp is. It matters most for FUT, where a tighter scalp limits how wide a strip can be closed without tension.
Scalp micropigmentation (SMP): Tattooing pigment into the scalp to mimic the appearance of shaved stubble or to add the illusion of density. It adds no hair and grows nothing; it is a cosmetic camouflage.
Scarring alopecia: Conditions in which the follicle is permanently destroyed by inflammation and replaced by scar tissue. Requires prompt medical treatment.
Sebaceous gland: The oil gland attached to each follicle. It is part of the follicular unit and travels with the graft.
Seborrhoeic dermatitis: A common inflammatory scalp condition causing flaking, redness and itching. It does not cause hereditary hair loss, but active inflammation is usually settled before surgery.
Second session: A planned additional procedure, usually at least a year later, to add density or address further loss. Planning for one from the start is different from needing one because the first was over-promised.
Shedding phase: The normal loss of transplanted hairs in the weeks after surgery, before the follicle re-enters growth. The follicle stays; only the shaft is shed.
Shock loss: Temporary loss of transplanted and sometimes surrounding hair in the weeks after the operation. Entirely normal and temporary.
Single-hair grafts: Grafts carrying one hair, used along the hairline to create a soft, irregular transition. Using multi-hair grafts at the front is a common cause of an unnatural result.
SMP: Scalp micropigmentation, a cosmetic tattooing of the scalp that mimics follicles. It does not add hair.
Spironolactone: An antiandrogen used off-label for female pattern hair loss in some countries. It is not used in men for this purpose and requires medical supervision.
Strip harvesting: The extraction method used in FUT, in which a strip of scalp is removed from the donor area and dissected into individual follicular units under magnification.
SVF (stromal vascular fraction): A mixed cell population separated from a patient's own fat, studied as an injectable treatment for hair loss. Published trials are small but report improved hair density with no serious adverse events.
SVP: The abbreviation used on this site for a scalp vitamin protocol, a non-surgical supportive approach aimed at the scalp rather than a surgical treatment.
Telogen: The resting phase of the hair, lasting roughly 3 months, after which the hair sheds and is replaced by a new one.
Telogen effluvium: Diffuse, usually temporary hair loss in which many follicles are pushed into the resting phase at once after stress, illness, childbirth or a deficiency.
Temples: The areas on either side of the hairline, where hereditary hair loss typically begins with recession.
Temporal hair: The wedges of hair in front of the ears that frame the face. Restoring them affects how natural a hairline looks, and they are often overlooked in planning.
Terminal hair: The normal, thick and pigmented hair, as opposed to the thin vellus hairs.
The Ludwig scale: A three grade scale grading female hair loss, which is typically diffuse with a preserved hairline.
The Norwood scale: A seven stage scale grading male hereditary hair loss, from slight recession to the horseshoe shaped rim.
Topical finasteride: Finasteride formulated for application to the scalp, intended to lower scalp DHT with less systemic exposure. Evidence is growing but less extensive than for the oral form.
Traction alopecia: Hair loss caused by sustained pulling from tight hairstyles, braids or extensions.
Transection: Cutting or damaging a follicle during extraction so that it will not grow. The transection rate is a direct measure of extraction skill and equipment control.
Transection rate: The proportion of follicles damaged during extraction. A low transection rate is a sign of good technique.
Treatment plan in writing: An itemised offer stating graft count, technique, who operates, what is included and what is not. Verbal quotes cannot be compared or held to.
Trichophytic closure: A closure technique used in FUT in which the wound edges are trimmed so hair grows through the scar, making the line less visible.
Trichoscopy: Examination of the scalp and hairs with a dermatoscope. It shows follicle openings, shaft calibre and miniaturisation directly, and is a standard part of a proper diagnosis.
Trichotillomania: A compulsive hair-pulling disorder. It causes irregular patches of loss and is treated psychologically; transplantation is not appropriate while pulling continues.
TRT (testosterone replacement therapy): Prescribed testosterone treatment. It raises androgen levels and can accelerate hair loss in genetically susceptible people.
TSH (thyroid stimulating hormone): The blood test used to screen thyroid function. Both under- and overactive thyroid can cause diffuse hair shedding, which is why it is part of a standard hair-loss workup.
Tumescence: Injecting fluid under the scalp before extraction or site creation. It firms the tissue, lifts follicles into a more even plane and reduces bleeding.
Vellus hair: The very thin, short and pale hairs that miniaturised follicles produce before they stop altogether.
Vertex (crown): The crown, the upper rear area of the head, where hair grows in a whorl. Hair loss often begins here as a circle, and because the hair grows in a spiral the area can consume a large number of grafts for a given visual effect.
Vitamin D: A nutrient repeatedly associated with hair loss in observational studies. Correcting a confirmed deficiency is where supplementation has a rationale; adding it on top of normal levels does not have the same support.
Weighted criteria: Scoring clinics against defined, published factors with stated weights, rather than ranking by reputation or advertising spend.
Widow's peak: A naturally occurring V-shaped point at the centre of the hairline. Whether to rebuild one is a design decision, since it reads as natural on some faces and artificial on others.
Yield: The proportion of transplanted hairs that grow, used in the literature much as graft survival is, and the figure clinic marketing most often quotes without stating how it was measured.
Zinc: A mineral whose deficiency can contribute to hair shedding. As with other nutrients, correction helps where a deficiency is measured; supplementing normal levels has little supporting evidence.

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Glossary: hair loss and hair transplantation from A to Z

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