Differentiating anemia of chronic kidney disease and anemia from other causes

How to differentiate anemia of chronic kidney disease from anemia due to other causes bearing in mind that patients with chronic kidney disease often have many comorbidities?

Francesco Locatelli: This is in a way a difficult question. The only problem is to look at the renal function. To have anemia related to chronic kidney disease, the patient should have deterioration in renal function. But that is not enough, because as you suggested, there are so many comorbidities and you should exclude any other causes of anemia. So if there are no other causes and there is renal insufficiency, by definition this is anemia related to chronic kidney disease.