Each one of the hairs on your head independently goes through a growth cycle consisting of three phases: Anagen (3-6 years), catagen (1-2 years) and telogen (2 -4 months)
Anagen is the active phase working to produce the hair fiber. The Catagen phase begins after the Anagen phase and is characterized by a state of inactivity, at this stage the hair follicle may lose its thickness. The telogen phase is the resting phase, the hair follicle is dormant and growth does not occur.
Average normal daily scalp hair loss in an adult is 40 to 100 hairs on a nonshampoo day and 200 to 300 hairs on a shampoo day. Each hair that is shed is replaced by a new hair. Scalp hair thinning only becomes noticeable after losing >50% of the normal scalp hair density. Overall, this leads to a gap between the initiating causes and the actual assessment.
The scalp is a rich environment for many microbes and the health of the scalp can affect the natural growth and retention of hair, appropriate scalp care may deliver fundamental benefits for hair growth and quality. Using hair care products with activities that reduce the populations of microbes that are known to cause scalp problems may be of benefit
Having rapid shedding or hair loss has been associated with low calorie diets and low protein diets. Hair loss can start 1-3 months after a dieting phase, which can confuse people as to the role of their diet in their hair loss.
Keeping your caloric intake at maintenance and ensuring that your protein levels are adequate can help prevent your nutrition from interfering with your hair growth and may encourage fuller hair in the future.
Pattern hair loss is almost completely related to genetics, however you may benefit from making small adjustments to your nutrition to support your genetic tendency for thinner hair.
Iron. There are theories as to why hair is more sensitive to iron deficiency than other tissues. It has been proposed that because hair is one of the most rapidly dividing cells that it is more sensitive to minor deficiencies of iron than other tissue types. The takeaway is that ferritin is lower in people who are experiencing hair loss. Get your ferritin checked.
Types of hair loss are scarring and non-scarring. Non scarring is the most prevalent, examples include telogen effluvium TE, pattern hair loss (male and female “androgenic”) and alopecia areata. Scarring I won’t be discussing.
HAIR LOSS IS A SYMPTOM, NOT A DIAGNOSIS
Telogen effluvium TE typically caused by a metabolic or other stressor such as dieting, infection, stress, hormone changes, (loss of estrogen, postpartum, discontinuing oral contraception) and hypothyroidism. Shedding in telogen effluvium happens 2-3 months after the trigger event.
Hair enters the telogen phase and stops growing for 1-3 months. After this resting phase, the re-entry to the anagen phase causes hair loss often months after the “event”. With TE there is often diffuse hair loss over the entire scalp.
Androgenetic alopecia hair loss has a higher production of dihydrotestosterone, which has an affinity for the androgen receptor. For women this sign of pattern hair loss may not present until after a TE event.
Pattern hair loss is predominately genetic, and will affect up to 50% of both the male and
Female population. With male and female pattern hair loss, the same pathologic process appears to be present and is characterized by a reduction in the duration of the anagen phase and an increase in percentage of hairs in the telogen phase. The follicles then also undergo a process of miniaturization that will determine progressive scalp hair loss. Genetically, male and female hair loss appear to be distinct. 20-30% of patients with polycystic ovary syndrome report female pattern hair loss. There is a cardiometabolic picture in men with pattern hair loss.
In female pattern hair loss it has been suggested there is possibly a protective effect of estrogens on human hair growth with increased prevalence of female pattern hair loss following menopause and prolongation of anagen during pregnancy
Several studies have also found that inflammation is common in pattern hair loss.
Alopecia areata is considered autoimmune based. Hashimoto thyroiditis, diabetes mellitus, lupus, and celiac disease, hypothyroidism and vitiligo are comorbidities with the strongest associations. Patchy hair loss pattern classically occurs in AA. Smoking is a lifestyle risk factor associated with AA and sleep disturbance especially in people older than 45 years. The treatment of alopecia is costly, they have to be done long term, and the clinical outcome is generally poor. You need to weigh up the pros/cons risk/benefit of each treatment and take into consideration the length of treatment and likelihood of complying to long term.
In practice the use of combine multiple treatment options should be considered with your health care professional
- Topical shampoos containing caffeine or pyrithione zinc
- Treatment with low light laser therapy and microneedling
- Correcting any nutritional deficiencies