So to summarize, when to start a phosphate binder in chronic kidney disease. There's no evidence-based medicine to help us answer this question, and if you do any of those choices listed at the beginning, you're not doing anything wrong, because we don't know clinically what the answer is. All we have is our physiology-based hypothesis approach. We do know 3 things. We know the body works very hard in CKD to maintain serum phosphorus levels within a tight range. We know that hormones responsible for that include PTH, FGF-23, other hormones we don't understand, and a rise in the urine phosphorus. And it's possible that there are cardiovascular and bone consequences of having to have this high level of all these hormones in your blood to keep your phosphorus level normal in CKD. So, it would make physiologic sense that decreasing the phosphate load in chronic kidney disease would help take the pressure off all these hormonal systems and possibly could improve health outcomes, but we don't know if that's true and we need to test that hypothesis in a well-designed clinical trial.
