You must be the IPL practitioner since you "have a client," and since most physicians call the recipients of their care "patients," I worry that you may have insufficient knowledge about a number of concerns. Appropriate treatment of the Addison's is the first step. Once this is stable, the hyperpigmentation typically remains, and only then is pigmentation reduction appropriate.IPL is NOT a laser, so the fact that you confuse this basic fact in your question is another concern. If you are a physician, I would humbly suggest that you obtain more training. If you are not, please talk with your physician medical director, but only if s/he is sufficiently experienced to answer this question for you.Finally, the best results in this setting would more likely be achieved with a chemical peel, which would leave much more uniform results without the checker-boarding that IPL can yield, especially with dark skin. Best wishes! Dr. Tholen