Hair loss

Hair loss: causes and biological assessment

Hair loss in a nutshell

We have about 1 million hair follicles on the skull. These follicles will constantly produce new hair during a long and cyclical growth. Each cycle will inevitably end with the loss of the hair formed. Normal hair loss is estimated between 30 and 150 hairs per day, but it varies greatly from one individual to another. This fallen hair is constantly renewed, which preserves hair density. This balance can however be broken and it can happen that we lose our hair in a significant and more or less brutal way. Some analyses carried out by your laboratory can be useful to know the cause of this hair loss.

hair physiology

The development of hair by the hair follicles is cyclical because it includes three phases:

  • A long growth phase (anagen phase) lasts between 3 to 6 years.
  • A phase of a few weeks corresponding to the cessation of hair growth (catagen phase)
  • A resting phase (telogen phase) leads to hair loss and lasts between 2 and 6 months.

Thus, hair follicles are not all in the same development cycle.

In return, this uninterrupted growth requires nutrients: growth factors, iron, amino acids, zinc, and vitamins. Certain hormones (thyroid, estrogen) stimulate the growth of follicles. Conversely, androgens (male hormones derived from testosterone) shorten the length of the hair development cycle.

Definition and main causes of alopecia

Alopecia is defined by a decrease in the number of hairs (which may go as far as their disappearance).

The causes of hair loss are numerous and it is sometimes difficult to identify the origin. However, we can cite:

  • Alopecia of genetic origin (rare)
  • Destruction of the follicle: trauma, burns, autoimmune diseases, ringworm. Ringworms are fungi that attack the scalp.
  • Abnormalities of hair growth production:
  • Telogen effluvium: it corresponds to significant and sudden hair loss after significant stress or childbirth, for example. The sudden loss can also find its origin in hormonal disorders (in particular thyroid), a deficiency in iron, zinc, and certain vitamins, and malnutrition…
  • Chemotherapies
  • Alopecia areata: autoimmune reaction causing damage to the hair follicle and sudden hair loss, often localized
  • Excessive styling habits (buns, too frequent brushing)
  • Androgenic alopecia (or androgenetic alopecia): baldness

The two most common causes are telogen effluvium and androgenetic alopecia.

Seasonal hair loss and telogen effluvium

Telogen effluvium is a common cause of hair loss, especially in women. Involvement occurs all over the scalp. The scalp remains healthy and these damages remain reversible.

This fall can be triggered in the following months:

  • A delivery
  • infection, high fever
  • Certain inflammatory diseases
  • An operation
  • Certain medications
Hair loss

There may also be physiological and seasonal hair loss, especially in autumn and spring. This alopecia, which is relatively common in women, is followed by normal regrowth and does not require any particular treatment. However, this loss often hides significant stress. Psychological support from your doctor or a psychologist may sometimes be necessary.

However, this fall can persist over time, causing hair thinning, especially in women with fine hair. The search for other causes must then be considered: recent intake of new drugs, presence of deficiencies in particular due to an unbalanced diet, hormonal disorders in particular thyroid disorders.

In this case, biological analyzes can be carried out on a simple blood test: the dosage of iron or ferritin, zinc, and vitamin B9 (folates). The doctor can then supplement you with the nutrients needed to correct the deficiency.

Complete and more specific assessments also exist, such as the vitamin assessment.

The vitamin balance sheet will allow you to know the profile of the vitamins present in your blood and you will thus have a global vision of your needs or even your deficiencies. This assessment will be able to guide you with the help of your doctor toward a change in your eating habits or nutritional supplementation.

Androgenetic (or androgenic) alopecia: CAL

Baldness is the most common cause of alopecia. In humans, its diagnosis is purely clinical (based on examination of the scalp by the doctor and interrogation) and often reveals a hereditary character. The age of onset of baldness is very variable. It can be very early, at the end of adolescence. It mainly affects men, but women can also be affected.

In men, hair loss is initially well defined: forehead and temples. The loss then extends to the upper part of the skull (the vertex) until finally giving an aspect of tonsure.

Treatments exist (local or general) but none allow hair regrowth. They are only suspensive, that is to say, when treatment is stopped, the benefit is lost. In addition, the potential effects are only visible after 6 to 12 months of treatment.

In women, baldness is very rare and its evolution is very slow. It must seek hyperandrogenism, that is to say, an increase in male hormones including testosterone. The causes are variable: diseases affecting the ovaries or the adrenal glands, and drugs with side effects that increase testosterone.

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