Although in our study one bolus injection of recombinant Klotho at the chosen dose did not improve anemia and iron deficiency in CKD, it does not exclude the possibility that suppression of Klotho levels deteriorates CKD-associated anemia and, thus, optimization of the treatment protocol may provide evidence that Klotho may still be a potential therapeutic target for renal anemia. This evidence concerns the gene KL and anemia (phenotype).