The sister of St Kilda champion Nick Riewoldt, Madeleine Riewoldt, has died at the age of 26.

Ms Riewoldt had been battling aplastic anaemia, a disease of the bone marrow, for the past five years.

She died at the Royal Melbourne Hospital on Tuesday morning surrounded by her family.

“We are so proud of Madeleine for fighting as long and hard as she did,” the Riewoldt family said in a statement.

“This spirit is a testament to her strength, she inspired us and so many and will continue to do so.

“We are grateful for and cherish the 26 years we shared as a family and she will remain in our hearts always.”

Ms Riewoldt’s wish was for a greater awareness of the need for people to sign up to the bone marrow registry and of blood donation.

The Riewoldt family has asked for privacy to grieve.