Here’s a good discussion about what happens when you do all your editing adjustments on an uncalibrated monitor, then send the image away to be printed. The important point is that if you keep your image in RAW (as in Lightroom) during editing, but then Export it as a jpg for printing, any post-editing by the printers will inevitably lose colour information.
You can demonstrate to yourself what might happen. Partially process a RAW image in Lightroom. Now Export it as a jpg. Now process it some more. If you watch what happens to the histogram you’ll see the dreaded comb effect appear, indicating that colour information has been lost in some areas. How do I know? Because I’ve done it myself more than a few times!
The moral of the story: make sure that your Exported image needs NO further edits before printing. That means “what you see is what you get”. And that means that your monitor and printer are calibrated. If you haven’t done so already, it’s time to spend a little money on a calibration device (Spyder or X-Rite). Or make sure that the place where you have your printing done offers a full service – that is, they will sit with you and your edited RAW file, in front of a calibrated monitor, and make any adjustments you wish, to get the image looking exactly the way you want it. before printing (DP Photography and Fine Art Printing in 100 Mile House offers this service).
Read the article – it’s worth it.