Savannah Rennie is on pace to graduate from one of the top public universities in the world.

She’s also thriving on the Cal volleyball team after overcoming a life-threatening illness. Twice.

Fewer than 10 matches into the season, Rennie already has earned Pac-12 Conference Player of the Week and tournament MVP honors. All of this, just two years after getting back on the court following a liver transplant and about a year after beating cancer.

“I’m starting to feel like myself again,” the 6-foot-2 senior media-studies major said. “I always knew I would get back. I just didn’t know when. There was never a definite answer of how long it would take.

“It depends on how much work you’re willing to put in, and it takes an unbelievable amount of work to get back from rock bottom twice.”

Rock bottom was an altogether unfamiliar place for Rennie, who grew up as a multisport athlete in San Diego. At 2, she taught herself to skate to Cher’s “Believe,” so that she could play hockey with her older brother.

By the fourth grade, Rennie was wearing size 10 women’s shoes, and in the fifth grade, she towered over her classmates and was taller than her 5-9 teacher. She dominated boys as a pitcher and catcher in one of Southern California’s top baseball leagues for most of her youth and turned herself into one of the nation’s best high school volleyball players.

Rennie was playing for the U.S. Youth National Team and was considered a top-20 recruit when she decided to skip the Torrey Pines-San Diego prom, graduate early and enroll at Cal for the spring semester in 2015.

“I played her my junior year of high school at a tournament of top teams in Santa Barbara, and I was in awe of her,” Cal teammate Bailee Huizenga said. “No one had ever seen a volleyball player like that. Her demeanor on the court and the way she carried herself was so incredible. Anyone would be intimated.

“To know what it was like playing against her on the other side of the court, at this point, I’m like: ‘Thank God she’s on my team, because she’s such a lethal threat.’”

Rennie was expected to start for Cal as a true freshman in the fall of 2015 and begin what seemed destined to become a decorated college career. But while training at home during the summer that year, she started feeling sick.

Scary sick.

She was nauseous, had thought-halting headaches and a 105-degree temperature. The pain in her abdominal region was nearly unbearable, because her organs were so enlarged.

After weeks of confusion, including a visit to her primary care doctor and four trips to urgent care, Rennie was admitted to the hospital. A series of tests finally revealed the diagnosis: congenital hepatic fibrosis, a condition of the bile ducts and renal system, with portal hypertension, which impairs the flow of blood from the gastrointestinal tract.

Cal volleyball Thursday: St. Mary’s at Cal, 7 p.m. P12BA Saturday: Cal at St. Mary’s, 5 p.m. (no TV)

Read More

The disease often is seen in infants and the elderly. Certainly not in teen athletes in their prime who barely had been burdened by even a common cold.

Rennie sat out the 2015 season as she tried to manage the disease with medication. When she contracted cholangitis — an infection of the tubes that carry bile from the liver to the gallbladder and intestines — and was becoming septic, it was clear that she needed a liver transplant.

Because it could take five years to get a transplant in California, Rennie and her mother moved to Indianapolis in March 2016. While attending a Cal baseball game in May at Northwestern, Rennie got the call about a liver donation.

She made the 200-mile trek from Chicago to Indianapolis and was at the hospital by 11 p.m. The surgery started at 6 a.m. the next day, and took only two hours, despite the doctors having to retract Rennie’s ribs to remove the extremely inflamed liver.

Two days after the transplant, the doctors performed another procedure. The next day, Rennie was walking laps in the hospital and trying to convince physical therapists that she could ride a stationary bike.

As soon as she got the go-ahead to return to California, Rennie and her father packed the car and started to drive — remembering to call the leasing office of their Indianapolis apartment only after they were already on the road.

On Oct. 7, 2016, fewer than five months after the transplant, Rennie made her college debut against Utah.

“She’s an absolute animal,” said Rennie’s brother, Luc, who is a pitcher in the Mets’ farm system. He cursed only twice during an emotional, 30-minute interview, but the magnitude of her recovery deserved the emphasis. “I don’t even know how she does that s—, man. She’s f—ing incredible.”

But during the spring of 2017, volleyball’s offseason, Rennie realized her body wasn’t recovering properly after workouts. It wasn’t just that she was tired, she was exhausted.

She had no appetite and started losing weight. The pain in her abdomen got so bad that there were days when she couldn’t get out of bed.

Refusing to accept that something else might be wrong, Rennie had to be forcibly taken to the Stanford emergency room by her boyfriend. She was diagnosed with non-Hodgkin post-transplant lymphoma, a rare cancer caused by the anti-rejection medicine she needed after the liver transplant.

Rennie locked herself in her room and wouldn’t talk to friends.

“‘Why me? Why now? What did I do?’” Rennie remembers thinking. She charted months of pristine living, following doctors’ orders and perfecting her nutrition before realizing it wasn’t anyone’s fault. “I had a lot of questions, but those things have to go away when you can’t answer them.

“You have to turn your mind-set to beating it. There are only two options: Either fight or give up. I was going to fight. I’m a fighter. That’s what I was going to do.”

Rennie had surgery to remove the fast-growing mass in her abdomen in July 2017 and underwent four infusions of antibodies. The treatment was only about 50 percent successful, so she started chemotherapy.

Even while undergoing chemo, which she said made her feel like she was walking around in a “dead body,” Rennie continued going to classes and rarely missed volleyball practices. Unable to participate much, she would shag balls for her teammates and occasionally try to make light passes that left her arms bruised and battered.

“Going to volleyball practice was the one thing that was good and normal,” she said. “Just being able to walk through double doors and be around what you love. Just being able to tie your laces and put on knee pads.”

Rennie was going through the darkest days of her life, but when she sensed a teammate struggling, it was Rennie who did the consoling. She has a strong ability to read people, a skill that will help her in her future career as a coach or broadcaster and sets her apart on the court as she seems to know exactly what opponents are planning to do.

Even when taking photos for this story, Rennie would read the photographer’s eyes and adjust her body before receiving direction.

Haas Pavilion has become Rennie’s sanctuary, and she made her return from cancer Sept. 7, 2018, recording six kills and two blocks against Portland State. She finished her junior season with 27 kills, 14 blocks and 10 digs, but she felt like a shell of the player she was projected to become.

Her own worst critic, Rennie beat herself up. Her thoughts were abusive and she even would berate herself for not playing up to her standards.

“The physical parts were never hard, but the mental stuff has been tough,” she said. “I would think: ‘I’m not who I was, so who am I?’”

Rennie was deemed “dominant” in a disc personality test. She describes herself as “blunt, bossy and stubborn” — the very traits that got her intentionally drilled by opposing pitchers in youth baseball, and the very traits that conquered two medical traumas.

Rennie is well aware of how she might be perceived, but she’s not about to change for anyone.

“It’s who I am every day,” she said. “I take what I do seriously, and I take it to the D. I don’t skip a detail. I do it with 100% passion all the time. That’s what you’re going to get from me. I won’t let anything derail me.”

It’s certainly working for Cal right now. Led by Rennie, the Bears are 8-0, their best start since 2013.

After winning the North Dakota State tournament last week, they entered the national rankings at No. 24. They’ll play a home-and-home with St. Mary’s (4-4) on Thursday and Saturday, and then start their loaded Pac-12 slate against No. 2 Stanford next Thursday.

“We’re underdogs,” Rennie said. “We know that. We love that mentality. It’s going to be super fun to prove that we’re not. We’re going to prove it day in and day out.”

Playing in a conference with six nationally ranked teams, Cal might be considered underdogs by most people.

Luc Rennie is not most people.

“I don’t marvel at this. I grew up with Savannah, so I expect this,” he said. “… Savannah went through some things that weren’t her choice, but she decided that she wasn’t going to give up, wasn’t going to roll over, wasn’t going to give into the things that hurt and the things that suck.

“Out of great suffering comes great success.”

Rusty Simmons is a San Francisco Chronicle staff writer. Email: rsimmons@sfchronicle.com Twitter: @Rusty_SFChron