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How Men Lose Hair

The most common form of hair loss in men is called male pattern hair loss. The development of male pattern hair loss depends on male hormones (androgens) and a genetic predisposition (hereditary factors).

Norwood-Hamilton chart showing various stages of male pattern hair loss

What is 'Male Pattern Hair Loss'?
Male pattern hair loss is a strikingly widespread condition (responsible for 90% - 95% of hair loss in men). It occurs in 25% of men by age 25 and 50% of men by age 50. With male pattern hair loss, your hair begins to thin at the temples and at the crown. As time goes on, the hair at the temples recedes further, leaving a central spur of hair at the front, and an increasing bald spot at the crown. Eventually the areas of hair loss at the front and crown meet, and the top of the head becomes increasingly bald. All that remains is a border of hair around the side and back of the head.

Male pattern hair loss or common baldnes is an androgen (male hormone) mediated hair loss that occur in genetically predisposed individuals. The key androgen is dihydrotestosterone (DHT) which is produced from testosterone by 5 alpha-reductase (an enzyme).

How Hormones affects Normal Hair Growth

The hair roots receive nutrients from blood vessels which contain blood cells (red) and hormone called testosterone (blue). Testosterone is converted to another hormone called DHT (yellow) by the actions of an enzyme called 5 alpha-reductase (5αR)

When high levels of DHT are present in the scalps of men who are genetically predisposed to male pattern hair loss, the following happens:

1. Shortening of the Growing Phase (Anagen Stage)
2. Progressive shrinkage of hair follicles, making hair shorter, finer and lighter.
3. Decreases the number of visible hairs.