She needed a kidney donor. She found one in the comments of her TikTok.

Nearly a year after her kidneys went into failure, Katie Hallum was waiting on a list for a new organ while undergoing dialysis. Looking for levity in the situation, the Oklahoma native posted a TikTok in July 2022.

"POV: I overhear you say you have an O blood type and healthy kidneys," the caption read. Then, Hallum lip-synced a line from "The Mandalorian": "You have something I want."

More than 300 miles away in Kansas, the TikTok appeared on Savannah Stallbaumer's "For You" feed. Stallbaumer, a licensed practical nurse, had seen patients struggling with dialysis, and she wanted to help.

"How do I get tested?" Stallbaumer commented.

Hallum wasn't expecting to find a kidney donor through the social media app, and she felt bad about the idea of a stranger sacrificing their organ. She figured she would eventually get a kidney from a deceased donor. But Hallum sent Stallbaumer the contact information for her Tulsa hospital's transplant center, figuring their blood wouldn't match anyway.

But it did. Things progressed from there: In August, Stallbaumer donated her left kidney to Hallum after they had met in person only a few times.

Hallum, 21, said she has almost fully recovered as she reaches the midway point of her senior year at the University of Oklahoma, where she's studying journalism and international security. She and Stallbaumer, 22, have become close friends since being introduced on TikTok, and this year, they're planning to spend Christmas together.

"Having the kidney in her is like an unbreakable bond," Stallbaumer told The Washington Post. "That's kind of weird to say, but she has a piece of my body in her body."

"I'm like 5 percent Savannah now," Hallum added.

Hallum first knew that something was wrong in March 2020 when she noticed that her ankles were swollen and her urine was red. She said she visited a hospital in Tahlequah, Okla., where she was diagnosed with IgA nephropathy, a disease that occurs when antibodies accumulate in the kidneys, damaging them in the process.

Hallum was starting her sophomore year in September 2021 when she came down with a throbbing migraine. Her blood pressure was high, so she drove to the hospital, where she said she suffered a seizure in the lobby.

During her roughly eight-day hospital visit, Hallum said doctors told her that her kidneys had failed but that they could still recover. While visiting her parents in Tahlequah two months later, however, Hallum said she suffered another seizure and visited a different hospital. This time, she said her nephrologist told her that she would need dialysis treatment to survive.

Hallum got on a list for a new kidney, but she said the wait time was between two to five years. Every night, Hallum connected a tube from her dialysis machine to her abdomen.

Hallum used TikTok to joke about her kidneys, once flipping a coin to guess whether her kidneys would go into failure and another time quipping that her condition might help her get scholarship money. She posted the video with the "The Mandalorian" voice-over in July 2022.

After seeing Hallum's TikTok, Stallbaumer reflected on times she wished she could've offered more help to those living with serious medical conditions. While working at a medical center earlier in 2022, she'd overheard someone say they would rather die than continue dialysis. She also thought back to elementary school, when her friend was diagnosed with bone cancer and it felt like all she could do was ask him how his chemotherapy was going.

In the week after Stallbaumer commented on the TikTok, she thought about Hallum daily. Hallum said she ignored Stallbaumer's message requests for a few weeks, but last September, Hallum gave her blessing for Stallbaumer to get her blood and body tissues tested.

"I just want to let you know you 100% don't have to do this," Hallum wrote. "Honestly I have no idea what to say - it's unlikely we'll be a tissue match but it's so astounding to me you'd even WANT to donate."

In the following months, Stallbaumer underwent blood and urine tests, X-rays, electrocardiograms, and CT and renal scans.

When Stallbaumer drove about four hours from her home in Silver Lake, Kan., to Tulsa for exams in April, she met Hallum for the first time at a Mexican restaurant. Over rice and beans, the two learned more about each other, discussing everything from their romantic relationships to their favorite foods. Later that month, Stallbaumer learned that she and Hallum had matched for a transplant.

Stallbaumer, who had recently graduated from the Washburn Institute of Technology in Topeka, Kan., said doctors asked her dozens of questions to ensure she was committed to donating the organ: What if you need the kidney in the future? Would you regret it if you went into kidney failure? What if Katie's body rejects the kidney right away?

She said another doctor didn't know what TikTok was and was confused when Stallbaumer said that she and Hallum had never spoken on the phone. But Stallbaumer said nothing would stop her from helping Hallum.

In July, Stallbaumer scheduled a transplant appointment for the next month at Ascension St. John Medical Center in Tulsa. A few days later, Hallum was out to dinner with her parents when Stallbaumer surprised her by tapping her right shoulder from behind.

Stallbaumer was holding flowers and a white sign that alluded to Hallum's interest in journalism.

"The official statement has been released: 'YOU'RE GETTING A NEW KIDNEY!'" the sign read.

Hallum erupted into tears.

On Aug. 16, the night before the surgery, Stallbaumer drove to Tulsa and planned to drop off a care package at Hallum's Airbnb. The two ended up talking most of the night.

The next morning, Stallbaumer was being rolled into surgery when Hallum told her again that she didn't need to go through with the procedure.

"I'm too drugged to back out now," Stallbaumer joked.

The transplant was successful, and Hallum and Stallbaumer were discharged in the following days. Hallum recovered at home before returning to college about a month ago. She said she now takes 11 pills daily - about half of what she took immediately after the transplant - and has more energy than she has had in years.

Stallbaumer will begin studying at Manhattan Area Technical College in Manhattan, Kan., in January to become a registered nurse. She hopes to work in oncology or dialysis.

Hallum said she would probably still be waiting for a kidney if Stallbaumer didn't volunteer.

"I do not know if words would ever fully describe how appreciative I am of Savannah," Hallum said.