[Objective assessment of therapeutic hair growth--methods, possibilities and problems].

With regard to hair growth induced by therapeutics, we have to consider various aspects of the activity of the hair follicle. This means that a study on the efficacy of hair growth therapeutics requires a selective investigation of different kinds of follicular activity. The decision which of the non-invasive, semi-invasive or invasive techniques available should be applied in a specific case depends on the reliability of the method in relation to the technical requirement, on the one hand, and the acceptance by the volunteer as well as the clinical type and degree of hair loss, on the other. Trichorhizogram results as the only means of evaluating the efficacy of hair growth therapeutics seem problematical, since an increase of the anagen rate does not absolutely correlate with a prolongation of the anagen phase.