The average amount of time a person spends on the kidney transplant list is three to five years, according to KidneyLink. A number of factors, such as blood type and health changes, can affect how long any individual waits.
Before a transplant can begin, the people participating in the transplant must have matching blood types, states KidneyLink. Additionally, both participants must have matching HLA, or human leukocyte antigen, factors. HLA is a genetic marker located on a person's white blood cells. Each person has three, and the more that match, the longer a transplanted kidney lasts. Finally, technicians combine samples of the participants' blood to observe any reactions. If occur, then the recipient may receive the kidney.