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 analyzes 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) that 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) leading to hair loss and lasting 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, 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 (up to 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 the 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, certain vitamins, 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 tellogen 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
  • 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: dosage of iron or ferritin, zinc, 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 can thus guide you, with the help of your doctor, towards a change in your eating habits or nutritional supplementation.


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