Androgenetic Alopecia, also known as Male-Pattern Baldness, is the most common cause of hair loss. About 50% of men will experience this form of hair loss by the time they’re 50 years old. As far as the ages in which baldness can occur, it can start as early as 12 and as late as 45. Though essentially benign, there are psychosocial effects that male-pattern baldness can cause. A major determinant of AGA concerns testosterone (T), more specifically the enzymes that affect androgen metabolism. In men, testosterone plays a key role in the development of male reproductive tissues such as the testis and prostate as well as promoting secondary sexual characteristics such as increased muscle, bone mass, and the growth of body hair.
Hair follicles produce both thick terminal hair and fine vellus hair. Vellus hairs develop on most of the human body form childhood, regardless of sex. At puberty, vellus hairs are replaced by terminal hairs in certain areas of the body, such as the axilla, pubis, and face; and this change occurs by the influence of androgenetic hormones. As far as the difference in size between these two types of hairs, hairs that grow <0.03mm in diameter and <1 cm in length are considered vellus, while those that longer are considered terminal hairs. When it comes to AGA, a characteristic of it is the conversion of thick terminal hairs into miniaturized, vellus-like hairs.
Hair Miniaturization can be easily defined as when the hair becomes thinner, shrinking in volume and growth length. For the most part, it is caused by AGA, or Male Pattern Baldness. The main mechanism for miniaturization relates to the shortening of the anagen phase, thus the hair becomes “lazy” and does not grow to its full term.
HAIR LOSS CAUSES IN MEN
Genetic
- Male pattern baldness, also known as androgenetic alopecia (a genetic condition)
- Heredity/family history of hair loss
Non-Genetic
- Extreme stress
- Side effects from medications
- Medical illnesses (thyroid conditions or systemic diseases such as lupus)
- Traction hair loss, also known as traction alopecia (from excessive pulling and braiding)
- Burn or major surgery scars
- Nutritional deficiencies (poor diet, iron deficiency, etc.)
- Hormonal imbalances (pregnancy, menopause, birth control pills)
THE NORWOOD HAIR SCALE
THE SEVEN STAGES OF HAIR LOSS INCLUDE:
- Stage 1: No significant hair loss or recession of the hairline.
- Stage 2: There is a slight recession of the hairline around the temples. This is also known as an adult or mature hairline.
- Stage 3: The first signs of clinically significant balding appear. The hairline becomes deeply recessed at both temples, resembling an M, U, or V shape. The recessed spots are completely bare or sparsely covered in hair.
- Stage 3 Vertex: The hairline stays at stage 2, but there is significant hair loss on the top of the scalp (the vertex).
- Stage 4: The hairline recession is more severe than in stage 2, and there is sparse hair or no hair on the vertex. The two areas of hair loss are separated by a band of hair that connects to the hair remaining on the sides of the scalp.
- Stage 5: The two areas of hair loss are larger than in stage 4. They are still separated, but the band of hair between them is narrower and sparser.
- Stage 6: The balding areas at the temples join with the balding area at the vertex. The band of hair across the top of the head is gone or sparse.
- Stage 7: The most severe stage of hair loss, only a band of hair going around the sides of the head remains. This hair is usually not dense and may be fine.
- Norwood Class A: The class A variation of the Norwood scale is a slightly different and less common progression of hair loss. The main differences are that the hairline recedes back uniformly, without leaving an island of hair in the middle, and there is no bald area at the vertex. Instead, the hairline progresses directly from front to back.