I know some skin issues like folliculitis and keratosis pilaris can cause hair thinning and loss. Both have to do with the skin. Folliculitis is an infection of the hair follicles. This is usually caused by bacteria and you need to kill it off to get the infection out. KP on the other hand, is calcium being used in place of vitamin A to make new skin cells. This causes the skin to be too tough for the hair to poke through and leads to ingrown hairs all over the body.