Dear Jane, the blood test I was referring to is a fractionated alkaline phosphatase with can show where the major component of the elevated alkaline phosphatase is coming from with liver and bone the two major determinants of an elevated alkaline phosphatase but it can also come from other sites as well.
With an elevated Ca, low PO4 and high PTH and elevated alkaline phosphatase, as a patient, I would want to know what is precisely the cause which should be fairly easily determined with the appropriate tests by your medical team to offer you the best treatment options. The issue of mineral bone disease and the impact that nocturnal dialysis has on it is not a settled issue at this point that I can see from my review of the studies I have read to date.
Once again, with the varied causes of these elevations, sorting out the precise cause would be one of my priorities if I faced that issue myself. Establishing whether it is primarily liver or bone alakline phosphatase elevation is usually the first decision point in most protocols involved in looking at these issues.
Once again, Dr. Agar has much more direct experience in this in the dialysis and nocturnal dialysis population than I do and I am sure he has much more to add to this.