You only have to look at your hairbrush or shower drain to see that we all lose hair on a daily basis. Today, as every day, you will lose about 100 hairs but they are usually replaced by new hair growth at around the same rate. However, when the hair follicles stop replacing the lost hair, you will start to notice thinning hair at one or more places on your head.
There are two main causes of thinning hair; genetic factors and other medical and physical factors. Most cases of thinning hair fall into the first category and, despite what the snake oil sellers would have you believe, there is little that can be done about it.
A large proportion of people experience some degree of hair thinning as they grow older, with some men seeing pattern baldness appearing as early as their late teens.
This article on causes of thinning hair and hair loss is by Kathryn Senior, a freelance journalist who writes health, medical, biological, and pharmaceutical articles for national and international journals, newsletters and web sites.
Hormones and thinning hair
Thinning hair as a result of genetic predisposition is known as androgenic alopecia. This can affect both men and women, although men will experience thinning hair in specific areas, such as on the crown or as a receding hairline, called pattern baldness, whereas women will tend to have more general thinning.
The process requires three factors to produce thinning hair: the hormone testosterone, genetically high levels of a hormone called 5-alpha reductase, and time for the effects of the process to appear.
5-alpha reductase converts testosterone in the blood stream into dihydrotestosterone (DHT), which starts to shrink the hair follicles. As they reduce in size over time, their growth cycle also reduces, producing weaker, thinner hair. Eventually, the hair follicle will reduce to the size it was when you were born.
Your levels of 5-alpha reductase will vary depending on your family tree – although it is worth remembering that you inherit these traits from both sides, so even if your father kept a full head of hair, you may still inherit thinning hair from your mother’s blood line.
Studies have shown that wider genetic factors, such as race and skin colour, also affect thinning hair. Caucasian males are far more likely to experience thinning hair than oriental or African-American males.