Former Ohio State student Karl Ludwig (left) stands next to lecturer Aaron Gall following their kidney transplant at Ohio State University Wexner Medical Center Sept. 1. Credit: Gretchen Klinger

Type B blood is one of the rarest blood forms in the U.S. 

For Ohio State sport fitness and health instructor Aaron Gall, his blood type became a stumbling block after an unexpected diagnosis of a kidney disease 10 years ago. 

Little did he know, a student of his would literally “save his life”. 

Gall’s transparency partially motivated Karl Ludwig, a former student in Gall’s eskrima — the national martial art of the Philippines — course, to get tested as a possible donor, leading to a positive match, ultimately saving Gall an estimated five to seven years of waiting for a deceased donor kidney. 

In 2013, Gall discovered his kidney issues by chance. 

A fall while at a birthday party caused him to hit his head, leading to a doctor’s appointment for a possible concussion. Instead, Gall said the checkup revealed he had high blood pressure, and further testing led to the discovery that he was operating at only a 35 percent kidney function.  

Gall said this abrupt diagnosis was a complete shock but caused him to change his eating habits immediately. 

“After that, I started really making sure that I was focused on my health and eating right,” Gall said. “Even though I did all those things and had my blood pressure finally in check, it was still just a slow decline.”

Despite his stern regimen, Gall said eight years later his kidney function had declined to 9 percent. His rare blood type put the chances of finding a viable deceased donor at an estimated wait of five to seven years.

Conversations of dialysis soon emerged as Gall’s kidneys were struggling to perform their normal functions, including filtering waste and toxins out of his blood. 

With the goal of staying off the medical procedure, Gall said he made an even more massive diet change, shifting to a vegan and renal diet, he said.  Until December 2022, his stern discipline allowed him to avoid dialysis, however, a checkup later that month revealed his potassium levels were too high. 

And without a donor in sight, it was time to head in that direction, he said. 

Dialysis became a daily part of Gall’s life along with his other responsibilities. Throughout the spring 2023 semester, Gall said he received at-home dialysis treatments while teaching full-time classes at Ohio State centered on physical activity. 

According to the National Kidney Foundation, hemodialysis is a treatment that uses a special filter called a dialyzer to clear waste and extra fluid from the blood. The procedure occurs at least three times per week and consists of two needles inserted into the patient. 

Even with the unpleasant side effects, Gall said he was forthright to his students about the diagnosis and the complications that coincided, he said.    

“When I was teaching, I was very transparent with my students about what was going on in case I needed to cancel class for an appointment or had complications,” Gall said.  

According to the Mayo Clinc, the side effects for a patient on dialysis can range anywhere from tiredness and itchy skin to muscle cramps. Gall said low energy was a major complication for him, and it didn’t help that he had to follow a strict diet. 

What Gall didn’t realize was that a student of his, Karl Ludwig, was secretly testing to become a possible donor. 

Karl Ludwig said he’d always imagined donating a kidney at “some point in his life.” The opportunity presented itself sooner than expected when Gall was transparent with the class about his disease, he said. 

“I’ve heard stories of people who donated their kidneys, and the concept of it really resonated with me,” Karl Ludwig said. “It’s always something I thought I might do at some point in my life, and then there was this person in front of me who needed one.”

During the semester his sister, Grace Ludwig, who is a nurse at Cincinnati Children’s Hospital, shared with him the experience of families who’ve lost a loved one who chose organ donation. 

“She talked to me as a way of processing because it was such a profound experience for her, and that sort of rekindled all of the thoughts I had previously about the impact organ donation can have on someone’s life,” Karl Ludwig said. 

His sister’s story coincided with a difficult medical day in class for Gall, in which he was once again open with his students. This inspired Karl Ludwig to visit a form Gall had linked in his Instagram bio that donors could submit to get tested for possible blood matches. 

“Walking home from class, I found myself clicking on the link and filling it out, like what the heck, worst-case scenario I find out my blood type and it doesn’t match,” Karl Ludwig said. 

The next day, he said he received a call from the transplant center to schedule an appointment to do preliminary blood work. 

He set an appointment that same week, and the results confirmed his wildest beliefs. It was a match, he said. 

Despite this result, Karl Ludwig said he had to go through several further evaluations throughout the semester to ensure he was a solid candidate for donation. 

“I had my last appointment of the testing process in early May, right before I graduated, doing all this while taking his class, which he thinks is so funny now that we were interacting every week,” Karl Ludwig said. “I remember walking to his class one day with a hospital bracelet on from one of my appointments and taking it off before I walked in.” 

Karl Ludwig said a few days after graduation, while in London, he received a call from the doctors. He had finally been cleared and was able to move forward with the transplant process, he said. 

Karl Ludwig said he returned to the U.S. that same day and met with Gall for coffee in German Village.  His text message beforehand said, “He had something that he wanted to give him that he hadn’t had the chance to before he left for the semester.”

The surgery took place Sept. 1. 

Karl Ludwig was released two days later and Gall the following Tuesday. Aside from a few minor complications, he said the recovery went smoothly and has been a unique bonding experience for them both. 

“His recovery is a bit more major and there are different factors to consider, but we’ve been really in touch because, in a way, we’ve been going through similar things,” Karl Ludwig said. 

Since the transplant, Gall said he’s returned to teaching in a verbal capacity. 

“You can’t keep me away from it,” Gall said.  “I probably should have taken a bit more time, but I wanted to get back because I just enjoy teaching. I enjoy making an impact and helping those in the classroom to have a release from everything they’re dealing with in college.” 

Gall said he hopes to resume in-person teaching in the next three to six months and is already feeling the difference physically since the surgery. 

“Now that I’ve got this new kidney, my energy levels are at a point where I feel like I could run a marathon,” he said. “I can’t imagine what it will be like when I’m fully healed up. I feel bad for the students actually, I don’t think they’re gonna be ready.” 

After six weeks on leave, Karl Ludwig has since returned to work at Ohio State’s Fisher College of Business, where he teaches students leadership skills through outdoor experiences in the Fisher’s Leading Expeditions Program. He said he believes his donation was worth every bit of his recovery and hiatus from normal activities, he said. 

“My sacrifice, both short term and long term, has been pretty insignificant compared to the positive impact it can make on the other end,” Karl Ludwig said. “So much good has come into my life from it, it doesn’t feel like a sacrifice at all.”