According to Clinical Interventions on Aging, less than 45% of women will maintain a full head of hair throughout their lifetime. While there are various causes of female hair loss, the most common is androgenetic alopecia or female pattern hair loss. Similar to male pattern hair loss, both heredity and hormones seem to play major roles in female pattern hair loss. However, patterns of hair loss appear differently in women than in men. Whereas male pattern hair loss typically concentrates at the front of the hairline and at the crown of the head, women with androgenetic alopecia more often have diffuse thinning on all areas of the scalp.
Once the cause of the hair loss is determined, the next step in figuring out the best course of treatment is to evaluate the extent of the hair loss. Several scales measure the extent of female hair loss, but the two most common standards are the Ludwig Scale and the Savin Scale. The two are almost identical, except the Savin Scale measures overall thinning as well as the density in the hair, shown by the hair pictured at the crown.
Stages I-1, I-2, I-3, I-4: illustrate the female crown hair density. The first stage (I-1) shows a woman with a central part in her hair with no hair loss. The part widens in images I-2, I-3, and I-4, demonstrating thinning hair along the top of the scalp and the crown area.
Stages II-1, II-2: show increasingly thin hair at the top of the scalp as the hair loss advances.
Stage III: represents a woman with severe female pattern hair loss, concentrated at the top of the head and crown area.
Advanced: while rarely seen in clinical practice, this picture shows a very advanced stage of female pattern hair loss, with almost no hair remaining on the crown or top of the head.
Frontal: demonstrates female pattern hair loss concentrated more at the forehead area than the crown of the head and gradually moves back. This pattern is fairly rare among women who experience hair loss.