In our present study, we did not observe any link between endometriosis and vitamin D or vitamin D-binding protein. A reason for this finding may be that there were few cases and the results therefore could not reach statistical significance. In ongoing follow-up studies, the number of cases has been increased to augment the statistical power of the research.

As you said, the revised American Society for Reproductive Medicine (rASRM) classification has the advantages of being easy to use and being the most widely used system, but it has the disadvantage of not reflecting severity, certain locations (such as cul-de-sac lesions), or deep-infiltration lesions [3]. We agree that the Enzian classification is an alternative that addresses the disadvantages of the rASRM classification [4]. In order to apply the Enzian classification, however, the total number of patients would need to be increased. In addition, patient classification requires effort to describe findings in a purely morphological manner.

In accordance with your opinions, follow-up studies are planned with the goals of obtaining meaningful results regarding the role of vitamin D in the pathogenesis of endometriosis and exploring the role of vitamin D as a therapeutic agent.