These observations suggest that (1) extended follow-up period should be implicated in clinical trials with CKD patients using PHIs; (2) the pro-calcification effect of other PHIs should also be tested; and (3) zinc plasma levels should be closely monitored parallel with EPO and hemoglobin levels in patients during the administration FG4592 or other PHIs, and zinc supplementation might be considered. This evidence concerns the gene EPO and chronic kidney disease.