Alongside an image of herself and her mother, Lattanzi wrote: "Hey everyone. I just wanted to let u know my mum is ok for those that have enquired. She's a fighter. Always has been."
She then thanked those who had enquired about her mother's condition. "Thank u for your love and concern. I'm passing your love onto her. Thank you guys. We love you," she wrote.
Fans were alerted about the Grease star's condition on her official Facebook page on Tuesday May 10.
"We are so sorry to announce that the Olivia concerts scheduled for May will be postponed due to a bad issue with Olivia's sciatica," the 68-year-old's management wrote at the time.
"Once the dates are rescheduled we will post the new dates ASAP. Apologies for any inconvenience."
Sending well wished to the Australian singer well during this time.