Hair Loss

Hair Loss

What is Hair Loss?

Pattern hair loss (androgenetic alopecia) is a medical condition characterized by progressive hair loss and thinning at the vertex, temporal regions, and frontal region of the scalp in men.  The disease may also affect women (female pattern baldness), causing loss of hair at the midline of the scalp.  It is caused by a combination of genetic factors and elevated androgens levels in scalp tissue.

The condition usually affects men who have gone through puberty, most commonly around age 18-40.  Women are usually affected after menopause (age 50) and have a slightly different pattern of hair loss.  The condition can be cosmetically displeasing and lead to psychological embarrassment and loss of self-confidence and self-esteem.

Interestingly, male pattern hair loss is associated with heart disease.

What Causes Hair Loss?

Pattern hair loss (androgenetic alopecia) is caused by genetic factors and elevated levels of DHT in scalp tissue.  It is not only passed on by the mother as many people claim – in fact, genes from both parents are important for the development this condition.

Testosterone is converted into DHT by the enzyme 5-alpha reductase.  This enzyme in located in high quantities in scalp tissue and the prostate.  In the scalp, DHT acts on hair follicles causing them to undergo a process called miniaturization.  This means that the hair follicles shrink because they spend less time in the growth phase – eventually dying off.

Pattern hair loss is also likely related to poor circulation in the scalp tissue.  High DHT levels and poor circulation are important principals in thinning hair as the treatment of this condition attempts to reverse these two processes.

How Common is Hair Loss?

This is an extremely common condition that is often evaluated in the primary care clinic.  The disease frequently requires referral to a specialist such as a dermatologist or plastic surgeon.

In the United States, it affects up to 50% of all Caucasian men by age 50 and 80% of males by age 80.  Up to 50% of women will develop female pattern hair loss during their lifetime.

Signs and Symptoms

In men, the most common symptoms of male pattern baldness in the following distribution:

  • Vertex – crown of head
  • Both temples
  • Frontal region

Men typically develop an M shaped pattern of  hair thinning.  As opposed to men, women typically develop hair loss or thinning in the central or midline region of their scalp.  The frontal hair line in usually spared.

Some women develop loss of hair due to hyperandrogenism – a condition characterized by elevated androgen levels – resulting in irregular menses, acne, and hirsutism.  Hirsutism is the development of hair in areas that usually appear in men, such as the face, inner thighs, and back.


Androgenetic alopecia is diagnosed based on symptoms and physical examination.  Your doctor may order blood tests to rule out certain conditions that can contribute to loss of hair.  This may include:

  • Iron deficiency (e.g., hemoglobin, iron levels, total iron binding capacity, ferritin),
  • Thyroid disease (e.g., TSH, free T4),
  • Syphilis (e.g., RPR).

If you are a woman with abnormal menstrual periods, infertility, significant acne, or facial hair - your doctor may work you up for hyperandrogenism.  This condition is evaluated by checking your testosterone, dehydroepiandrosterone sulfate, and prolactin levels.

Hair Loss Treatment and Medication

In men older than 18 years, the most common treatment for pattern hair loss includes:

Rogaine (minoxidil) works by dilating the blood vessel in the scalp.  This promotes increased blood flow to the scalp tissue, thereby encouraging hair follicle health and hair growth.  It is usually applied topically to the scalp twice daily.  It is available in shampoo, gel, and cream formulations.

Propecia (finasteride) is an oral medication that works by inhibiting the enzyme 5-alpha reductase.  This results in less conversion of testosterone to DHT.  Remember - DHT promotes hair follicle miniaturization and hair loss – therefore, Propecia prevents hair loss by reducing DHT levels.  Finasteride is also used in patients with benign prostatic hyperplasia (BPH) – which is a common condition in older men characterized by an enlarged prostate and urinary symptoms.

DHT is important for sexual function – therefore, 5-alpha reductase inhibitors such as Propecia (finasteride) may produce undesirable side effects such as decreased libido, erectile dysfunction, and problems with ejaculation.

Propecia (finasteride) is not usually effective in treating hair loss in women.  Most women with androgenetic alopecia benefit from topical Rogaine (minoxidil) therapy – similar to men. In women in a hyperandrogenic state, Aldactone (spironolactone) may be effective as it inhibits androgen receptors.

People who are not interested in any of the aforementioned medications may decide to use toupees, hair pieces, hair extensions, or wigs.  Some individuals may benefit from hair transplantation or insertion of hair plugs.


  1. Varothai S, Bergfeld WF. Androgenetic alopecia: an evidence-based treatment update. Am J Clin Dermatol. 2014 Jul;15(3):217-30. -
  2. Rathnayake D, Sinclair R. Male androgenetic alopecia. Expert Opin Pharmacother. 2010 Jun;11(8):1295-304. -

Hair Loss Treatment

The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.