When a person goes to a specialist upon observing symptoms of hair loss, it is possible that the specialist asks for a lab study in order to achieve a precise and definitive diagnosis or to monitor the evolution of the disease. This study is called “trichogram” and belongs to the branch “trichology,” which is a part of dermatology dedicated to the study of scalp hair. Learn what the cause is.

Science has created areas of research for each aspect of human life. Therefore, we see dermatology, which studies the skin and its layers, but a more specific part of dermatology, trichology, studies all that is related to hair and scalp.

What is trichology?

As we mentioned before, trichology is a part of dermatology in charge of researching, analysing and studying the inherent aspects of the scalp and scalp hair in terms of the main characteristics of the hair, such as the colour, density, quantity and the structure in order to achieve a precise diagnosis regarding its state.

In this regard, this small scientific branch not only seeks to offer solutions to hair problems, it also aims to prevent these problems. For this reason, it uses diverse techniques and tests, such as dermatoscopy, the trichogram and the phototrichogram. The person in charge of carrying out these procedures is called a trichologist.



Trichogram is a medical inquiry technique directed towards obtaining information regarding the state of scalp hair in the different phases of its evolution. Therefore, the trichogram would be of great use to learn what the real state of our scalp hair is before learning what kind of hair treatment to use.

Its main advantage lies in providing precise data regarding scalp hair, which allows us to pick a medical procedure based on the characteristics and the needs of the patient’s hair. The study requires the collection of a hair sample in two parts: the root and the hair shaft.

These samples are observed and analysed with a microscope in order to determine the state of scalp hair and thus to know why the hair falls out. There are five forms or states in which the scalp hair can be: anagen, telogen, catagen, dysplastic and dystrophic.

The results of this study provide information regarding the anagen-telogen percentages, as well as the form, colour and outline of the roots, along with the diameter and the degree of angulation of the hair shaft.

The trichogram can be used on people of any age and it allows us to investigate problems with the scalp hair and scalp which present alopecia in any of its modalities. On the other hand, this exam is very helpful for the diagnosis of other hair diseases like follicular dysplasia -whether the nutritional or the genetic type-, the decline or increase in keratin levels, demodicosis, endocrine alopecia, colour dilution alopecia, as well as pigmentary disorders of hair growth.

Given the importance of this study, it is essential that it is conducted by a professional, considering that, as with any scientific procedure, a wrong result could put the patient in danger.

Scalp hair and its phases

In order to know how scalp hair works and evolves, it is necessary to remember that scalp hair completes a vital cycle, which is divided into three phases: the anagen, the catagen and the telogen.

Our head is formed by at least a hundred thousand hair follicles, which, in turn, have one to four strands of scalp hair. These follicles go through some twenty hair cycles, with the three phases mentioned before.

The anagen phase has a duration that varies between two to eight years and covers the formation process of scalp hair. After this, the follicles enter into a state of rest; this period is the catagen phase, which extends between four to six weeks, when the scalp hair starts to detach from the scalp, which is known as the telogen phase. Once two or three months have gone by, the cycle starts again.

A person with normal hair activity has 85% of their hair in the anagen phase, between 1% and 2% of the hair in the catagen phase, and a 13% of the hair in the telogen phase. Therefore, it is normal to lose between fifty to a hundred hair follicles per day. When people reach old age, the cycles become shorter, particularly on the upper part of the head, and the hair shafts lose their length, strength and density.

In androgenic alopecia, the activity period of the anagen phase shrinks excessively and important variations can be observed in the length and diameter of the hair shafts; a fundamental difference compared to the other types of alopecia.

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Brief overview of trichology or the study of scalp hair