Haemodialysis and Kidney Transplantation

Haemodialysis

The blood urea level rises abnormally (uraemia) in patients suffering from kidney failures. In such patients, an artificial kidney is used for removing excess urea from the blood by a process called haemodialysis.

Blood is taken out from the artery of the patient and cooled to 0°C. This blood is then passed through cellophane tubes of the artificial kidney. Cellophane is permeable to micro molecules such as urea, uric acid and mineral ions. It is not permeable to macromolecules such as plasma proteins.

Outside the cellophane tube is the dialyzing fluid, which has some solutes like those in blood plasma but no nitrogenous molecules like urea, and uric acid. Hence the nitrogenous compounds from within the cellophane tubes flow into the dialyzing fluid by diffusion. Blood coming out of the artificial kidney is warmed to the body temperature and returned to the vein of the patient.

Kidney Transplantation

If kidney failure cannot be treated by other available means, kidney transplantation is advised. Donated kidney may come from a living person or a donor who has recently died.

The genetic make up of the donor should be as close to the patient as possible, that is, if it is donated by a close relation, it reduces the chances of rejection. Drugs are, however, used to prevent rejection of the transplanted kidney by the body.