Male pattern hair loss (androgenetic alopecia) is a hereditary condition distinguished by a receding hairline and the disappearance of hair from the top of the head, eventually balding a part (“bald spot”) or the entire top of the scalp. It is the most common type of hair loss in humans and affects millions of men worldwide.

Many believe that male pattern hair loss is inherited as a dominant trait from the maternal side of the family. However, the genetic predisposition for male pattern hair loss is more likely attributed to a combination of multiple genes (polygenic), the action of androgens (male sex hormones) and increasing age. Other than possible emotional or psychological effects (e.g., depression), male pattern hair loss poses no health risks.

In addition to taking a patient’s complete medical history and performing a physical examination, a physician diagnoses male pattern hair loss by observing the total amount of hair on the scalp and analyzing how it is distributed. Additional testing may be performed (e.g., skin biopsy, blood tests) to check if other diseases that cause hair loss (e.g., alopecia areata, telogen effluvium) are also present.

There is no cure for male pattern hair loss. However, medical and surgical treatments are available that may grow hair or prevent further hair loss (e.g., minoxidil, hair transplantation).

Male pattern hair loss (androgenetic alopecia) is a hereditary condition distinguished by a receding hairline and the disappearance of hair from the top of the head (crown), eventually balding a part (“bald spot”) or the entire top of the scalp. The lower back and sides of the scalp are usually unaffected. The condition progresses gradually throughout a man’s lifetime. Generally, the earlier male pattern baldness begins, the greater the total hair loss over the course of a man’s lifetime. Male pattern baldness is the most common type of hair loss in humans, affecting millions of men worldwide. 

Hair is composed of a protein called keratin and is produced in hair follicles located in the outer layer of the skin (epidermis). Each person is born with a set amount of follicles, which hold the lower part of the hair shaft in place and contain blood vessels that stimulate new hair growth. The process is cyclical and happens in three stages:

• Growth (anagen) phase. May last two to three years for any given hair. On a normal scalp, about 80 to 90 percent of hair follicles are in the growth phase at any given time.
  
  
• Involutional (catagen) phase. Reduction in size of the hair. Approximately one to three percent of hair on the scalp is undergoing involution at any given moment. The involutional phase is a transitional period the hair undergoes before being shed. Typically, it lasts about two or three weeks.
  
  
• Resting (telogen) phase. Shedding of hair from the scalp. Following involution, hairs go through a resting phase for about two to three months. At the end of this time, the hairs are shed and the growth cycle is reinitiated. On a normal scalp, approximately five to 10 percent of hairs are in the resting phase at any given time, with about 75 hairs shed every day.
  
  

  

A full head of hair has about 100,000 hairs. An exception is redheads, who have fewer hairs, and blondes who have more. However, red and blonde hair tends to be thicker and to provide better coverage.

Up to 30 percent of hair may be lost by middle age as a normal part of the aging process. Male pattern hair loss is not typically noticeable until at least half of the hairs in a designated area have fallen out. The condition also causes remaining hairs to thin, making the appearance of hair loss more defined. 

At a genetically predetermined point, heredity triggers the production of an enzyme (a complex protein found in body cells) called 5-alpha reductase. When the androgen (male sex hormone) testosterone combines with this enzyme, dihydrotestosterone (DHT) is produced. DHT causes both the affected follicle and hair to shrink in size. Over time, this process miniaturizes follicles to the point that hair permanently falls out without chance of regrowth. A reduction of the levels of these chemicals in follicles works to help reverse the shrinking process and is the goal of certain medical treatments for male pattern hair loss (e.g., finasteride).

Men with male pattern hair loss typically experience a gradual transition over several years from thick, colored terminal hairs to soft, non-colored vellus hairs (“peach fuzz”). The onset of male pattern hair loss shortens the anagen phase while the telogen phase remains unchanged, causing hair to fall out faster than it can be regrown.

Many men experience a receding hairline (around the temples) in an M-shaped hair pattern, often progressing to partial or total baldness across the top of the scalp. Male pattern hair loss affects most men to some degree by age 60. The condition can occur in men of all racial and ethnic backgrounds. It is most common in Caucasians, with the lowest rates of incidence occurring in Native Americans. Men of Asian decent are also impacted less often.  

Other than possible emotional or psychological effects, male pattern hair loss poses no health risks. One exception, however, may be that a decrease in hair volume allows potentially damaging ultraviolet radiation to reach the scalp. Male pattern hair loss may cause some individuals to become introverted, have low self-esteem or feel unattractive or tense in public places. This is particularly true in men who begin to lose hair in their teenage years or early 20s (premature male pattern baldness), as these feelings tend to be more troubling in younger patients. Although treatment is not necessary, patients who are emotionally impacted by the condition may benefit from seeking treatment options.

Anecdotal evidence has long suggested that male pattern hair loss is inherited as a dominant trait from the maternal side of the family. However, the genetic predisposition for male pattern hair loss is more likely attributed to a combination of multiple genes (polygenic), the action of androgens (male sex hormones) and increasing age.

In addition to taking a patient’s complete medical history and performing a physical examination, a physician diagnoses male pattern hair loss by observing the total amount of hair on the scalp and analyzing how it is distributed. Men with the condition usually first lose hair on the top of the scalp (crown) and around the temples, making diagnosis relatively routine.

Charts depicting different stages of hair loss may be used in some cases. The Hamilton-Norwood classification chart breaks down the progression of male pattern hair loss into seven classes. Initial hair loss (stages 1 and 2) typically consists of a receding frontal hairline. This recession becomes more defined over the temples and crown area of the scalp in the intermediate period (stages 3-5). Finally, total hair loss over the top, upper sides and back of the scalp characterizes the most advanced progressions of the condition (stages 6-7). Modified versions of the system may be used for patients with different balding patterns.

Additional testing may be performed (e.g., skin biopsy, blood tests) to check if other hair conditions (e.g., alopecia areata, telogen effluvium) or certain illnesses that cause hair loss (e.g., hypothyroidism, hyperthyroidism, iron deficiency) may be responsible or occurring in conjunction with male pattern hair loss. Side effects from other medications a patient may be taking (e.g., anticoagulants, anticonvulsants, beta blockers, antidepressants) can also cause hair loss and should be considered.

Male pattern hair loss is not a serious medical condition. Therefore, treatment is not necessary. In fact, many men choose to let the condition run its course. Patients who are emotionally impacted by the condition, however, may benefit from seeking treatment.

There is no cure for male pattern hair loss. However, there are medications that may be recommended to treat current hair loss and to prevent further hair loss, including:

• Minoxidil. An over-the-counter medication that may be effective at treating male pattern hair loss. Available in liquid form or as foam, it stimulates hair growth by reversing the shrinking process that occurs in the hair follicle. Minoxidil must be used for several months before the patient sees any results. It is available in either a 2 percent or 5 percent solution, with the 5 percent solution being slightly more effective. However, minoxidil does not work for everyone. Persistent use of minoxidil is necessary for hair to grow, as it will most likely fall out once use is discontinued. Minoxidil may also prevent further hair loss because it enlarges hairs and makes them grow for a longer period of time.
  
  
• Finasteride. A prescription medication taken orally (by mouth). It may slow or stop hair loss in some patients. Others may see new hair growth after continued use. Finasteride inhibits the body’s ability to convert testosterone into dihydrotestosterone (DHT), the hormone that shrinks hair follicles and contributes significantly to hair loss. Like minoxidil, finasteride must be used for several months before taking effect and any benefits derived from the drug stop once use is discontinued.

In addition, medical and surgical treatments are available that may grow hair or slow the onset of baldness. Hair restoration surgery is a popular method that is often effective at creating a hairline that appears natural. Recent technological improvements have helped in creating safer and easier hair restoration techniques than in years past.

These include:

• Hair transplantation. Hair transplantation is the most popular surgical method of hair restoration. It involves transplanting healthy hair follicles from a “donor site” on the back or sides of the head to the bald or thinning area. Hair transplantation produces a natural look in many patients without visible evidence that surgery has been performed.
  
  
• Flap surgery. During a flap surgery, a section of bald scalp is removed and hair-growing scalp is stretched and sewn in its place, with hair growing to the edge of the incision. The size and placement of the flap depends on the individual patient. Flap surgery is designed to cover large areas of baldness.
  
  
• Scalp reduction. A physician performing a scalp reduction procedure removes an area of bald scalp and pulls forward sections of hair-growing scalp to fill in the bald area. Scalp reduction surgery may be used to cover areas at the top and back of the head, but is generally inappropriate for covering the frontal hairline

Men who begin to bald in their late teens or early 20s (premature male pattern baldness) may not be good candidates for hair restoration surgery. Men with this condition may be extraordinarily self-conscious about their appearance and may harbor unrealistic expectations of what hair restoration surgery can do for them. Because hair loss will progress over time, the production of a youthful looking hairline will likely look inappropriate later in life and is generally not advisable. Furthermore, the large amount of donor hairs required may cause the end result to seem unnatural and the patient to be dissatisfied with the results.

In addition, nonmedical methods such as wigs, hairpieces and weaves may effectively disguise hair loss. They may be made with either real or synthetic hair and are often the least expensive treatment method. In some cases, hairstyle changes can also help disguise the condition. However, these methods do not slow or stop the progression of further hair loss.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctors the following questions about male pattern hair loss:

1. How likely is my hair loss to continue?
   
   
2. What may be causing my hair loss?
   
   
3. Should I be tested for an underlying condition that may be causing hair loss?
   
   
4. Could my hair loss be in response to a medication I’m taking?
   
   
5. How effective are those “miracle cures” I see advertised on television?
   
   
6. What are my treatment options?
   
   
7. What happens if my transplants don’t “take”?
   
   
8. How much hair regrowth should I expect?
   
   
9. Are there any newer, more effective treatments currently in development?
   
   
10. What are the chances my children will experience pattern hair loss?
    
    
11. At what point should I abandon the use of medication if it is ineffective?