Kidney failure disrupts blood composition

1. Kidney failure occurs when the kidneys cannot filter the blood adequately or regulate its water and ion content.
2. Urea accumulates because it is not removed from the blood quickly enough.
3. Water and ion balance changes because selective reabsorption and urine formation no longer work effectively.
4. Untreated failure is dangerous because toxic waste and abnormal fluid balance disrupt cell and organ function.
5. The two main treatments are dialysis and a kidney transplant from an organ donor.

Dialysis removes wastes by diffusion

1. During dialysis blood is taken from the patient and passed through a machine before being returned.
2. A partially permeable membrane separates the blood from dialysis fluid.
3. The dialysis fluid contains no urea so urea diffuses from a higher concentration in the blood to a lower concentration in the fluid.
4. The dialysis fluid contains a normal glucose concentration so there is no net loss of glucose from healthy blood.
5. Its ion concentrations are controlled so excess ions can diffuse out while useful concentrations are maintained.
6. Fresh dialysis fluid flows continuously to maintain steep concentration gradients for diffusion.
7. The cleaned blood returns to the patient with less urea and a safer balance of dissolved substances.

Dialysis has repeated costs

1. Advantages include avoiding donor shortage and providing treatment without placing a donor organ in the patient.
2. Regular sessions are required because dialysis works only while the blood is connected to the machine.
3. Time and travel can restrict work, school, diet, fluid intake and daily life.
4. Risks include infection, blood clotting and sudden changes in blood pressure.
5. Dialysis can bridge the wait by keeping a patient alive until a suitable donor kidney becomes available.

A transplant replaces kidney function

1. A kidney transplant places a healthy kidney from a living or deceased donor into the patient.
2. A successful kidney filters the blood continuously, so regular dialysis is no longer needed.
3. Benefits can include fewer dietary restrictions, more freedom and lower long-term treatment costs.
4. Limits include donor shortage, a major operation and the possibility that the transplanted kidney will fail.

Tissue matching reduces rejection

1. Tissue rejection occurs when the immune system recognises antigens on the donor kidney as foreign and attacks the organ.
2. Tissue matching selects a donor whose antigens are as similar as possible to those of the recipient.
3. Immunosuppressant drugs reduce the immune response and lower the chance of rejection.
4. Reduced immunity increases susceptibility to infectious disease and makes long-term monitoring necessary.

Treatment choice depends on evidence

1. Dialysis may be preferred when no suitable donor is available or transplant surgery would carry a high risk.
2. A transplant may be preferred when a suitable kidney is available and the patient can tolerate surgery and immunosuppressant treatment.
3. A justified decision weighs effectiveness, availability, risks, lifestyle effects and long-term consequences for that patient.