Earlier this week, Selena Gomez revealed that she had had a kidney transplant with a kidney donated by her friend Francia Raísa. Gomez suffers from lupus, an autoimmune disease that often causes kidney function to decline severely, and underwent surgery this summer. She thanked Raísa in an emotional Instagram post, saying: “She gave me the ultimate gift and sacrifice by donating her kidney to me. I am incredibly blessed. I love you so much sis.”

Now, Raísa – an actress who, like Gomez, lives in Los Angeles – has shared her side of the story in a touching Instagram post of her own.

The kidney transplant was a matter of life and death for Gomez, said Raísa.

“I am beyond grateful that God would trust me with something that not only saved a life, but changed mine in the process,” she wrote.

In Gomez’s original post, the singer and actress said that she was looking forward to sharing her “journey through these past several months” with her fans. Raísa echoed that sentiment, saying that she and Gomez would be putting out more information about the surgery in due course.

“This was part of our story, and we will share it soon,” she said.

Read more: Selena Gomez pays tribute to best friend who gave her a kidney

However, Raísa also urged people to remember that Gomez is not the only person to suffer from lupus. The illness is estimated to affect at least five million people worldwide, and tends to predominantly affect women of childbearing age and people of Hispanic, Asian and Afro-Caribbean descent.

“What is important now is that this is not the only story,” wrote Raísa. “For more information regarding lupus, please go to the Lupus Research Alliance website: lupusresearch.org – Love you sis, so glad we’re on this journey together.”

Raísa and Gomez have been friends for eight years. On Gomez’s 25^th birthday in July, Raísa posted a throwback photo of the pair, paying tribute to their deep friendship in the caption.

“I went through heartbreak this year and you left the studio and drove out of your way to come see me and comfort me,” she wrote. “I received good news last month and you facetimed me minutes before you went up on stage just to congratulate me.”

Read more: Selena Gomez says that she ended friendships for the sake of her mental health

“There are so many moments we have and things you do that I cherish and don't take for granted.

“Whether it’s crying, laughing, or simply sitting on my kitchen floor throwing our hands up in the air confused at life, I'm thankful you're always there.”

Gomez first revealed that she had been diagnosed with lupus in October 2015, when she was just 23 years old. She told Billboard that she had gone through chemotherapy to combat the disease, which damages the body’s immune system.

A healthy immune system should produce proteins called antibodies, which protect the body from viruses, bacteria and germs. However, in the case of someone with lupus, the immune system creates autoantibodies, which attack and destroy healthy tissue. This can result in symptoms including extreme fatigue, painful joints and hair loss, and in severe cases can cause sufferers to develop other serious illnesses such as kidney disease and heart disease.

Lupus has also been linked to mental health issues, with many sufferers also experiencing generalised anxiety and depression. According to the organisation Lupus UK, this may be a reaction to the experience of having a long-term chronic illness, particularly one that makes it hard to live a ‘normal’ life.

Gomez entered a treatment facility for lupus-related anxiety and depression in 2016. Earlier this year, she said that she wanted other women to feel able to talk about their mental and physical health struggles.

“We girls, we’re taught to be almost too resilient, to be strong and sexy and cool and laid-back; the girl who’s down,” she said. “We also need to feel allowed to fall apart.”

For more information and advice on living with lupus, visit lupusuk.org.uk.

Images: instagram.com/franciaraisa