Generality
The trichogram is the microscopic examination of the hair. This semi-invasive procedure allows you to follow the life cycle of your hair, assessing your health and helping the dermatologist to identify the underlying causes of a possible alopecia.
How to do it
Before the exam
The trichogram, in itself, is a rather simple procedure, which however requires compliance with certain procedural standards to increase the reliability of the results. For example, to avoid misinterpretation, the patient is asked not to wash their hair for at least a week before the test. In view of the trichogram, frictions and cosmetic treatments such as undulations or permanent dyes should also be avoided for at least two weeks.
The exam
The trichogram begins with the removal, by tearing, of 50-100 hairs; also in this case the procedure must respect very precise rules. The tear, for example, must be rather decided and carried out in the direction of hair growth; otherwise it can cause structural deformation of the roots, invalidating the test results.
In the case of diffuse alopecia, the tear should be performed in the site of greater thinning, while in the face of alopecia areata cases it should be performed on the edge of the patch and in the contralateral area. In both cases, however, it is a good rule to proceed to a further tear from a control area, generally at the occipital level. In fact, for example, in the case of male androgenetic alopecia, the increase in the percentage of hair in telogen affected only the fronto-occipital areas, while in the case of telogen effluvium the phenomenon is spread to the whole scalp.
In the event that the patient suffers from seborrhea and / or hyperhidrosis, the collection must also be carried out in the temporal areas.
If, on the other hand, the patient suffers from dandruff, hair can only be taken in the nape area.
The hair sample is then placed on a slide covered with Peruvian balsam, with the hairs arranged parallel to each other. Cover with a coverslip and proceed with the examination with an optical or polarized light microscope. Thanks to the optical enlargements the dermatologist can evaluate in which growth phase the uncorked hair is found, observing its structure with particular attention at the level of the root.
deepening
Briefly, we recall that the life cycle of a hair consists of three contiguous phases:
Anagen : it is the growth phase, which affects at the same time percentages varying between 80% and 90% of the hair; its duration, of several months or even years, tends to decrease in the presence of androgenetic alopecia.
Catagen : it is the fall phase of the hair and lasts about two weeks.
Telogen : it is the resting phase of the hair that precedes the fall (catagen), and lasts about 100 days. The length of this period tends to increase in the presence of androgenetic alopecia, up to the inversion of the temporal relationship between anagen and catagen.
Once the roots of the preparation have been examined, the trichogram involves the meticulous counting of the number of hairs present in the various phases, followed by the calculation of the relative percentages.
According to the classic dictates, in the normal trichogram the percentages of the hair in the various phases correspond roughly to the following values:
- Anagen: 80-90% of the hair.
- Catagen: 1-2% of the hair.
- Telogen: 10-20% of the hair.
Diagnosis
Whatever the reference percentages (variable depending on the equipment used, the operator's experience, the time elapsed between microscopic sampling and examination, etc.), in the pathological trichograms there is a variation with respect to the standard values. This data, together with the clinical picture and anamnesis, represents a precious help in the formulation of a correct diagnosis.
In alopecia areata, for example, the roots have a dystrophic aspect in the easily recognizable anagen phase, while in the androgenetic alopecia the roots in the telogen phase are clearly higher than the norm.
Why do you run
The tricogramma is a very reliable test that allows to obtain precise information on the state of health of the hair, allowing to identify any anomalies and alterations in the normal life cycle of the same. Thanks to the information obtained from this examination, it is therefore possible to identify the causes of a possible hair loss, discriminating whether it is effluvium or defluvium and whether this thinning is taking place in the anagen or telogen phase.
Below, the main features of these different forms of hair loss will be described (for more information: Effluvio and Defluvio).
Once the type of thinning that afflicts the patient through the trichogram has been established, the doctor can prescribe further tests and analyzes in order to assess the cause of hair loss. Only in this way will it be possible to undertake the treatment - pharmacological and otherwise - that best suits each patient.
Effluvio in anagen
This condition occurs classically a few days after a particularly stressful event, such as poisoning, aproteic diet, chemotherapy, exposure to ionizing radiation or febrile diseases.
In predisposed subjects, these stressful events cause alopecia areata, which is characterized precisely by a heavy effluent in anagen. In any case, the fall is self-limiting and generally lost hair grows back spontaneously if the stressful event does not recur.
Tellu effluvium
It is possible to distinguish two different forms of telogen effluvium, acute and chronic.
Effluvium in acute telogen
It is also caused in this case by stressful and short-lived events, which however occurred not a few days, but about three months before the effluvium. The imposing loss of hair can be the result of surgical operations, bleeding, death or febrile illness. The phenomenon is self-limiting and tends to self-remedy, but in some cases, the dermatologist can still decide to prescribe corticosteroid-based drug therapy.
Effluvium in chronic telogen
In the chronic form of the telogen effluvium an important and relatively constant hair loss over time is appreciated. More common in women, it is generally linked to a chronic hair growth disorder, often with no tendency to spontaneous resolution. Among the main causes of chronic telogen we remember frequent donations of blood, serious mental illnesses, thyroidisms, chronic systemic diseases or prolonged use of some drugs (retinoids, interferon, heparin, some oral contraceptives, allopurinol ...).
The treatment of this form of effluvium involves the administration of corticosteroids topically or orally, depending on the severity of the clinical picture.
Defluvium in anagen
It is characterized by a hair loss above the norm, but without the dramatic characteristics of the effluvium. The thinning is due to the progressive loss of the follicles, secondary to their destruction. It is typical of cicatricial alopecias and can be the consequence of diseases such as lichen planus, discoid erythematous cutaneous lupus, alopecitating folliculitis, linear scleroderma (morphea), Broq pseudo-area, trichomalacia and radiation alopecia.
Flood in telogen
In most cases, hair loss is characterized by a flood of telogen. This is in fact the characteristic manifestation of androgenetic alopecia, a condition linked to the activity of androgenic hormones in a genetically predisposed medium. As anticipated, this disease is characterized by a moderate fall of the hair, accompanied by their gradual involution (they become increasingly thin, short and depigmented). Unlike the flood in anagen, in the androgenetic alopecia the follicle is preserved, but it becomes more and more superficial.
In addition to androgenetic alopecia, both male and female, in women the defluvium in telogen is also accompanied by states of hyperprolactinemia, anorexia nervosa and all forms of alopecia related to hyperandrogenism (polysitic ovary syndrome, androgenic secreting neoplasms ...) and / or hypoestrogenism (menopause, post-partum, suspension of the contraceptive pill ...).
For information on the treatment of the aforementioned forms of alopecia, we recommend reading the dedicated articles already present on this site.
