[QUOTE=Jane;19384]Hi Dr. Agar.
Trust you had a good vacation. My question today is what does it mean if alkaline phosphatase becomes very elevated with nocturnal txs and what causes it?[/QUOTE]
Let me jump in while Dr. Agar is out and about. Alkaline phosphatase is an enzyme found in bone and liver tissues primarily. There are many conditions that can cause the alkaline phosphatase level to become elevated. In dialysis patients, the mineral-bone disease brought on by secondary hyperparathyroidism is the usual cause of an elevated alkaline phosphatase caused by increase bone turn over. Going to nocturnal hemodialysis and extended treatments in many cases improves the mineral-bone metabolism lessening PO4 elevations and it usually reduces the need for phosphate binders as well as reduced need for vitamin D analogs that help control the vitamin D deficiency that is caused by renal failure. In such, PTH levels usually improve with switching to nocturnal dialysis regimens.
There are several simple tests that your medical team can look at to see if the elevation is related to bone or related to the liver. The first place to start with a dialysis patient is observing the relationships between PTH, PO4, Ca and alkaline phosphatase to see if it fits into a pattern associated with hyperparathyroidism. Many patients will eventually not respond to Vitamin D analogs or Sensipar and need to undergo parathyroidectomy to correct the underlying disorder of mineral bone disease. Once again, your nephrologist and your medical team should be able to observe the relationships between the factors listed above.
The difficult observation to make when faced with a clinical situation where we might expect elevations related to the renal disease is to always understand that there may be another process causing the elevation unrelated to the renal disease issue. Testing for liver enzyme abnormalities, obtaining liver imaging tests and other specific blood tests to exclude these rare entities should always be considered when evaluating elevations of alkaline phosphatase especially if modifying the renal related mineral-bone disease factors does not correct the elevation.
Fortunately, the majority of evaluations for an elevated alkaline phosphatase do not reveal any significant findings. Nevertheless, due to the many causes of an elevated alkaline phosphatase, a complete and thorough evaluation in every case should be completed expeditiously to identify what the specific cause is. Once again, the first place that the evaluation begins is determining whether it is an elevation due to liver or due to bone which is determined by a simple blood test.
I hope that this gives you some information to bring to your medical team for discussion of where to look further. I am sure that Dr. Agar can add further to this discussion.
Most sincerely,
Peter Laird, MD