Diane Chillingworth and Michelle Linden both found out in 2020, just two weeks apart, that they needed a kidney transplant.
They had previously been diagnosed with polycystic kidney disease (PKD).
Ms Linden was diagnosed after one of her cysts ruptured and she was taken to hospital and then had sepsis.
Ms Chillingworth was then tested and diagnosed.
The women, who describe themselves as "mirror images of each other", said that they were brought even closer together by the news that they needed transplants.
Those donations came from their siblings. Their sister Annarose McCartan and brother Noel Kielty donated a kidney each after being found to be matches.
In a further family twist, their nephew Liam Smyth, a medical student, had his first placement at the Ulster Hospital Renal Unit, and was able to see exactly what his aunts were experiencing.
Mr Smyth had also offered to donate a kidney, and was a match, but not as close as the siblings were.
He urged everyone to "speak to people and get educated" if they are thinking about donating their organs and describes the process as "invaluable".
Ms Chillingworth and Ms Linden said the staff were "fantastic", adding "they're like a family".
They said their lives have changed significantly since their successful transplants, and their energy levels are soaring.
They said: "There is nothing in this world that we could give Noel and Annarose to thank them for what they've done for us, because they gave us a new life."