What is your approach to an elevated alkaline phosphatase level in an ESKD patient with normal PTH, phosphorus, and calcium levels?  

I would approach this as any other patient with elevated AP. Is it new? LFTs normal or abnormal? What does the liver and skeleton look like? Etc.

I find that the PTH and alkaline phosphatase levels correlate pretty well in ESRD. Normal PTH for ESRD patients is 150-600 or higher, which is significantly higher than in the general population. I would be hesitant to attribute an elevated alkaline phosphatase level to anything other than bone dise...