Male-pattern hair loss (MPHL), also known as androgenic alopecia and male pattern baldness, is hair loss that occurs due to an underlying susceptibility of hair follicles to shrinkage due to the influence of androgenic hormones. Male-pattern hair loss is the most common cause of hair loss and will affect up to 70% of men and 40% of women at some point in their lifetimes. Men typically present with progressive hair loss at the temples and vertex balding, whereas women typically present with diffuse hair loss over the top of their scalps. Both genetic and environmental factors play a role, and many causes of male-pattern hair loss remain unknown.
Signs and symptoms
Classic male-pattern hair loss begins above the temples and vertex, or calvaria, of the scalp. As it progresses, a rim of hair at the sides and rear of the head remains. This has been referred to as a ‘Hippocratic wreath’, and rarely progresses to complete baldness. The Hamilton-Norwood scale has been developed to grade androgenic alopecia in males.
Female androgenic alopecia is known colloquially as “female pattern baldness”, although its characteristics can also occur in males. It more often causes diffuse thinning without hairline recession; similar to its male counterpart, female androgenic alopecia rarely leads to total hair loss. The Ludwig scale grades severity of androgenic alopecia in females.