The PTH of 47 is not your Prolactin. It is parathyroid hormone (PTH) levels. PTH is made by four tiny parathyroid glands in your neck. These glands control calcium levels in your blood.
Your Prolactin levels were 16 and 18.8 and all hormones will fluctuate. If you have sex and ejaculate the day before or on the day of your labs your Prolactin will be elevated but the same is true for your PSA but I do not see that the PSA was tested. If you are supplementing with arginine it can also elevate your prolactin levels.
It is possible that there is a tumor on the pituitary gland which can elevate prolactin levels but if that was the case I would expect the prolactin to be much higher than 16 to 18.8. This is something you should discuss with your doctor.