" The concentrations of urea and mineral ions build up in the body. The effects include: 1. Loss of electrolyte balance – if the kidneys fail, the body cannot excrete excess Na, K and Cl ions. This causes osmotic imbalances in the tissues and eventual death. 2. Build-up of toxic urea in the blood – if the kidneys fail, the body cannot get rid of urea and it can poison the cells. 3. High blood pressure – the kidneys maintains the water balance of the blood. If they fail, blood pressure increases, and causes a range of health problems including heart problems and strokes. 4. Weakened bones as the calcium/phosphorus balance in the blood is lost. 5. Pain and stiffness in joints as abnormal proteins build up in the blood. "