Haemodialysis and Kidney Transplantation: Renal Treatments

When kidneys fail irreversibly, wastes and extra fluid must be removed by treatment. Haemodialysis filters blood outside the body through a machine, while kidney transplantation replaces a failed kidney with a healthy donor kidney.

These treatments matter because end-stage kidney failure is fatal without them. Dialysis keeps a person alive but must be repeated regularly. Transplantation, when successful, offers better quality of life and freedom from dialysis, but needs lifelong medicines to prevent rejection.

Key Concepts

• Dialyser: The artificial kidney containing a semipermeable membrane across which wastes diffuse into dialysis fluid.
• Dialysate: Special fluid with controlled salts that draws wastes and excess water from blood.
• Vascular access: An arteriovenous fistula or graft in the arm that allows repeated high-flow blood withdrawal.
• Ultrafiltration: Removal of excess water during dialysis by pressure across the membrane.
• Immunosuppressants: Drugs given after transplant to stop the immune system attacking the donor kidney.
• Rejection: Immune damage to the transplanted kidney, which can be acute or chronic.

How It Works

1. In haemodialysis, blood is pumped from the patient through the dialyser at about 200 to 400 millilitres per minute.
2. Urea, creatinine, potassium and excess fluid move across the membrane into dialysate, which is discarded. Cleaned blood returns to the patient.
3. A typical session lasts about 4 hours, usually three times a week in a centre, though home schedules vary.
4. In transplantation, a donor kidney is placed in the lower abdomen and its artery, vein and ureter are connected. The patients own failed kidneys are often left in place.
5. After surgery, urine production may start immediately. Blood tests monitor function, and immunosuppressants are taken daily.

Worked Example

If a patient gains 2 kilograms between dialysis sessions, most of that is fluid, since 1 litre of water weighs about 1 kilogram. Excess fluid to remove = about 2 litres. Over a 4-hour session, ultrafiltration rate = 2000 millilitres ÷ 4 = 500 millilitres per hour. Removing fluid too fast can cause cramps and low blood pressure, so rate and session length are carefully prescribed.

Common Misconceptions

• Dialysis cures kidney failure: Wrong. It replaces filtration partly but does not restore the kidney or its hormone functions fully.
• Transplant means no more medicines: Wrong. Immunosuppressants are lifelong; stopping them can cause rejection.
• One dialysis session cleans blood permanently: Wrong. Wastes rebuild between sessions, so treatment repeats.

Real-World Applications

Peritoneal dialysis is an alternative using the abdominal lining as membrane at home. Transplant waiting lists use tissue matching and medical priority. Erythropoietin and vitamin D supplements replace other kidney functions that dialysis cannot. Organ donation after death can save multiple lives.

To conclude, haemodialysis sustains life by external filtration, and transplantation restores near-normal kidney function. Both require careful medical follow-up, diet and infection precautions.