If dialysis patients take in too much phosphorus, what will happen?

Itching. High phosphorus levels in a dialysis patient can lead to many issues. Usually most patients itch uncontrollably. However over time elevated phosphorus levels can alter bone structure, lead to calcium deposits on heart vessels and cause nerve damage throughout the body.
Damaging. Most dialysis patients with high phosphorus levels have no obvious short term complications, though they do exist. One very rare one is called calciphylaxis and is life threatening. Much more often patients notice itching. Long term is where the most damage is done. Damage is done to the blood vessels leading to faster heart disease and peripheral vascular disease as well as some bone diseases.