|Home Page||Dialysis Units||Clinic Locations||Office & Staff|
Phosphorus and calcium work together to keep your bones and teeth strong. Healthy kidneys remove extra phosphorus, so if you have kidney failure - even with hemodialysis - your levels may be too high. Too much phosphorus can cause itching, bone pain, brittle bones, muscle aches, and heart damage, so itís very important to make sure it doesnít build up in your blood.
As the phosphorus builds up in the blood it will irreversibly combine with
serum calcium making an insoluble product. This causes many problems. The
calcium-phosphate product will float in your blood stream coating everything
that it touches. It can coat and harden blood vessels and heart valves. The
calcium-phosphate can also dissolve out of the blood stream forming
little rocks under the skin. This is called calcyphylaxis. The exact cause
of calciphylaxis is poorly understood but has been found to involve
calcifications of small and medium blood vessels leading to cutaneous skin
necrosis. Lesions usually develop as a result of local skin trauma or at
injection sites. The early phase involves focal central skin death, often
surrounded by painful subcutaneous plaques and purpuric patches in a
reticulate pattern. The late phase includes dusky plaques with induration
that may progress into ulcers covered by thick, dark eschar that is very
tender and leads to necrosis. Lesions may be solitary or multiple, covering
several body regions.
These glands are responsible for maintaining a normal serum calcium by secreting a hormone called parathyroid hormone. This hormone has three functions that all will try to raise serum calcium concentration.
Mobilization of calcium from bone: Although the mechanisms remain obscure, a well-documented effect of parathyroid hormone is to stimulate osteoclasts to reabsorb bone mineral, liberating calcium into blood.
So.... High parathyroid hormone can lead to weakening of the bones.
In summary then, high serum phosphorus
causes phosphorus to bind with calcium leading to calcyphylaxis and to
lowering of the serum calcium level. This leads to elevation of parathyroid
hormone that removes calcium from the bones.
Most people on hemodialysis need to take a
phosphate binder to help control the level of phosphorus in their blood.
Phosphate binders "soak up" extra phosphorus from food before it reaches
your bloodstream. It then passes from your body in your stool. You take
phosphate binders along with meals and snacks. They may cause constipation
but you can ask your dietitian to suggest ways to increase fiber in your
diet to help. Be sure to tell your care team if you become constipated.