Selena Gomez has undergone a kidney transplant

Selena Gomez has taken to Instagram to share in an emotional post she's undergone a kidney transplant.

The 25-year-old pop star revealed she needed a new kidney because of her lupus diagnosis.

Selena received the "ultimate gift" in the form of a kidney from her longtime friend, actress Francia Raisa.

The transplant took place in the American summer and was a success.

The 'Bad Liar' hitmaker revealed her ordeal with her 126 million followers, sharing a photo of her and Francia holding hands in their hospital beds.

The accompanying post read: "I'm very aware some of my fans had noticed I was laying low for part of the summer and questioning why I wasn't promoting my new music, which I was extremely proud of. So I found out I needed to get a kidney transplant due to my Lupus and was recovering. It was what I needed to do for my overall health. I honestly look forward to sharing with you, soon my journey through these past several months as I have always wanted to do with you. "Until then I want to publicly thank my family and incredible team of doctors for everything they have done for me prior to and post-surgery. And finally, there aren't words to describe how I can possibly thank my beautiful friend Francia Raisa. She gave me the ultimate gift and sacrifice by donating her kidney to me. I am incredibly blessed. I love you so much sis. Lupus continues to be very misunderstood but progress is being made. For more information regarding Lupus please go to the Lupus Research Alliance website: www.lupusresearch.org/ (sic)"

In 2015, Selena revealed she had undergone chemotherapy to treat Lupus, a chronic auto-immune disease that attacks your healthy tissue and your organs.

And earlier this year, the brunette beauty opened up on her need for a career break in 2016 to deal with the "anxiety, panic attacks and depression" that her Lupus had also caused.