But the 26-year-old Mexican immigrant's goal is now trapped in the debate over a program protecting hundreds of thousands of immigrants like her from deportation.
Whether she becomes a doctor depends on whether Congress finds an alternative to the Deferred Action for Childhood Arrivals program that President Donald Trump phased out last month.
Arreola, who was brought to the US illegally at age 14, is among about 100 medical students nationwide who are enrolled in DACA, and many have become a powerful voice in the immigration debate.
"It's mostly a tragedy of wasted talent and resources," said Mark Kuczewski, who leads the medical education department at Loyola University's medical school, where Arreola is in her second year. "Our country will have said, 'You cannot go treat patients.'"
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The Chicago-area medical school was the first to openly accept DACA students and has the largest concentration nationwide at 32. California and New York also have significant populations, according to the Association of American Medical Colleges.
Then-President Barack Obama created DACA in 2012. Critics call it an illegal amnesty program that is taking jobs from U.S. citizens. In rescinding it last month, Trump gave lawmakers until March to come up with a replacement. Public support for DACA is wide.
A recent poll by The Associated Press-NORC Center for Public Affairs Research showed that just 1 in 5 Americans want to deport DACA recipients.
Arreola took a break from her studies last month to travel to Washington with fellow Loyola medical student and DACA recipient Cesar Montolongo Hernandez to talk to stakeholders. In their meetings with lawmakers, they framed the program as a medical necessity but also want a solution for others with DACA.
A 2017 report by the Association of American Medical Colleges predicts a shortfall of between about 35,000 and 83,000 doctors in 2025. That shortage is expected to increase with population growth and aging.
"I've shown I deserve to be here," said Hernandez, who met with Illinois Sen. Dick Durbin, a Democrat who's called for Congress to quickly pass a replacement for DACA.
For Arreola it's about returning to the state she's called home since she was 14 and giving back to areas in need of doctors.
"My family is from there; I know those people," Arreola said. "Those are the people that inspired to really give this a push."
Medical school administrators say the immigrant students stand out even among their accomplished peers: They're often bilingual and bicultural, have overcome adversity and are more likely to work with underserved populations or rural areas.
"They come with a cultural competency for how to best treat the individuals from their background, whether immigrants or different races and ethnicities," said Matthew Shick, a government relations director for the Association of American Medical Colleges. "That gets translated over to their peers in education and training."
Her DACA permit expires in January, and she's trying to renew it so she can continue medical school rotations that require clinical work. If she's able to work in US, Patel will work in disadvantaged areas of Illinois for four years, part of her agreement to get school loans.
"Growing up, I didn't have insurance," she said. "I knew what that felt like, being locked out of the whole system." For others, there's added worry of being stuck with debt they can't repay.
"Can I even afford to finish medical school?" said Zhou, who was 12 when she came to the US on a visitor visa that eventually expired. "It's sort of hard sometimes to keep going.