We do say PN is, or can be, a symptom of diabetes, celiac, certain kinds/types of toxicities, and other conditions. I took that to be what Steven meant -- that it is not necessarily an end in itself, but a symptom of something else to look for as a cause, even if/when that cause is not yet known. We've discussed this here before; PN can be either/or both a condition and/or a symptom, depending on context.

Doc