A 45-year-old patient on hemodialysis for one week has noted that his BP is more difficult to control. He reports good compliance with his medications, which include erythropoietin, ferrous sulfate, vancomycin, and vitamin D. His BP is 180/99 mm Hg. Most likely cause for the worsening control of his BP is?
Erythropoietin Ferrous sulfate Vancomycin Vitamin D