Clarke Thiesen’s legacy lives on through lifesaving blood donations

The first time strangers saved Clarke Thiesen’s life, her parents never saw their faces.

There were no introductions. No dramatic speeches. Just a hospital room, a devastating diagnosis and bags of donated blood being rushed toward a little girl.

Thiesen was not yet three years old when she was diagnosed with acute myeloid leukemia — AML — in October 2021. By the time doctors discovered it, her hemoglobin had fallen to a dangerously low level.

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“When we were in the hospital first, when Clarke was diagnosed, her hemoglobin was 50,” her mother, Cassandra Thiesen, recalled. “Anything under 70 is very, very dangerous. And so they gave her immediate transfusion.”

Clarke Theisen was two years old when she was first diagnosed with AML, a type of leukemia. (Submitted)

Until that moment, blood donation had existed somewhere far outside the boundaries of Cassandra’s everyday life.

“I had never donated blood in my life,” she said. “I was pregnant. I couldn’t even donate blood.”

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Then suddenly, blood — donated quietly by people she would likely never meet — became the thing keeping her daughter alive.

“We both just thought, ‘these strangers are saving our daughter,’” Cassandra said.

Months of Clarke Thiesen’s life were spent within the walls of the Jim Pattison Children’s Hospital in Saskatoon. (Submitted)

Over the next four years, strangers would save Thiesen again and again and again.

Transfusions became woven into the rhythm of childhood cancer treatment. More platelets. More hemoglobin. More waiting. More hoping. More impossible decisions placed into the hands of parents trying desperately to keep their little girl alive.

Thiesen eventually received more than 100 blood transfusions.

“After the 100, I honestly couldn’t keep track anymore,” Cassandra said.

But this is not a story that begins and ends in hospital rooms. Because before Thiesen became a patient, she was, first and always, Clarke. A little girl with enormous confidence. A little girl who knew exactly what she wanted. A little girl who carried joy into every room she entered.

Clarke Thiesen was the very proud big sister of Leo. (Submitted)

“Clarke was the most amazing person in the world,” Cassandra said. “She’s someone that you would aspire to be.”

She pauses for a moment when she talks about her daughter, as though every memory arrives all at once.

“She was so confident, but so kind and empathetic. She knew exactly what she wanted and how to get it. She was so sweet to everyone around her, so kind to her brother. She was so full of adventure and fun, and honestly, truly had the best zest of life.”

Even cancer could not take that from her.

She was a patient, but she was also a child. Clarke Thiesen did many of the things any other kid does, like holding a candy sale, within the walls of the hospital. (Submitted)

There were days when Thiesen’s platelet counts dropped so low that ordinary childhood activities became dangerous. Riding a bike. Falling down. Even losing a tooth carried risks because her blood could not clot properly.

But Thiesen, with the resilient logic only children possess, found ways to make even transfusions feel hopeful.

“When she would get platelets, she would always joke that she could be more dangerous,” Cassandra said with a laugh, “because mom would let her do things that she wouldn’t normally be allowed to do.”

It became one of those small, beautiful family truths that somehow survives even the darkest seasons: after transfusions, Thiesen got a little bit of freedom back. A little more childhood. A little more time.

Clarke Thiesen was a six-year-old girl with a zest for life. She passed away in April of 2025 after a four-year battle with leukemia. (Submitted)

Thiesen underwent two bone marrow transplants during her fight with leukemia. Through it all, blood donors, anonymous and unseen, remained a constant thread between fear and survival.

And then, in April of 2025, the little girl who had fought so hard slipped away.

For the Thiesen family, the arrival of April this year felt unbearable before it even began.

“We knew April was coming up, and we knew it’d be a really hard month for us,” Cassandra said.

Grief has a way of filling every corner of a home. It sits quietly at the dinner table. It lingers in empty bedrooms. It arrives unexpectedly in grocery store aisles and traffic lights and bedtime routines. But Cassandra explained that she has learned something about grief.

“Grief is love without a place to put it,” she said.

So she and her husband Riley started asking themselves a question: Where could they place all the love they still have for Clarke?

For four years, the Thiesen family navigated frequent admissions and long stays in the hospital as their daughter Clarke battled cancer. (Submitted)

The answer brought them back to the strangers who saved their daughter’s life. Together, they organized a blood drive in her honour through Canadian Blood Services.

“What better way to honour her life than honestly give the gift of life?” Cassandra said.

Their goal was deeply personal: 100 donations, matching the number of transfusions their daughter received during her life.

“At the beginning, my husband’s like, ‘That’s a crazy goal, Cass,’” she remembered.

Clarke Thiesen’s favourite show was PJ Masks. She could often be heard belting out the theme song in her hospital room. (Submitted)

There were reasons to doubt it. Many regular donors were ineligible because of donation timelines. Others faced restrictions from recent travel or tattoos. The family had not even been able to give people much notice.

But something extraordinary began happening.

People came.

Then more people came.

Friends shared posts. Families booked appointments. Community members who had never met Thiesen showed up simply because they had heard about a little girl whose life had depended on donated blood.

“The more we got, you got this collective feeling of everyone wanting to honour her and lift you up,” Cassandra said.

One year after their daughter’s passing, Cassandra and Riley Thiesen decided to hold a blood drive in her memory. (Submitted)

By the time the campaign ended, 128 people had successfully donated blood. More than 135 had tried.

“When we hit 50, I knew we were going to make 100,” Cassandra said. “You could just feel like everyone wanted to honour Clarke and support us.”

Inside donation clinics, people rolled up their sleeves for people they would never meet — just as strangers once did for Thiesen.

Only this time, her story was the reason.

The family plans to continue the blood drive every April. Thiesen’s sign still hangs at Canadian Blood Services in Saskatoon because, as Cassandra says, “People don’t just need blood in April.”

And the Thiesens are ensuring their daughter’s legacy reaches far beyond a single campaign.

Through the Forever Clarke Foundation, the family is supporting Saskatchewan families facing pediatric cancer by funding research, strengthening care at Jim Pattison Children’s Hospital’s Pediatric Oncology Clinic, advocating for better care and helping families directly.

The Thiesen family founded the Forever Clarke Foundation following their daughter’s passing. The non-profit supports Saskatchewan families facing pediatric cancer. (Jim Pattison Children’s Hospital Foundation/Facebook)

The foundation is built around the belief that Thiesen’s story is not over simply because her life ended.

It lives on in every blood donor who books an appointment. In every family sitting beside a hospital bed praying for another chance. In every child who may one day survive because research moved faster, care improved or blood was available when they needed it most.

“We don’t get to keep her,” Cassandra said softly. “And God, did she love helping others. So we just thought to honour her life, because she can’t be here, that if everyone was able to donate blood and to help someone else when they’re in need and when they’re going through their toughest days, that would be the most anyone could ask for.”

There is something profoundly beautiful about the way Thiesen continues to move through the world now. She’s in the hum of blood donation clinics. In the kindness of strangers. In the hands of people choosing, one donation at a time, to save someone they may never know.

Thanks to the efforts of her mom and dad, Clarke Thiesen, a little girl who loved helping others, still is.

After losing their daughter Clarke to leukemia, Cassandra and Riley Thiesen turned grief into hope, inspiring more than 100 blood donations and launching a legacy that continues saving lives. (Submitted)