A Monash University-led study assessed the blood results of patients who presented to The Alfred Hospital emergency department within six hours of injury.
The study found those diagnosed with concussion by a specialist also had significantly elevated blood protein levels.
The discovery could lead to a simple blood test that would take out human error when trying to diagnose the condition, study lead Stuart McDonald said.
"Even with the best intentions and honesty, there's still elements of subjectivity in the diagnosis," Dr McDonald told AAP.
"This is the case in sports concussion, particularly in community sports where there isn't video review and medical doctors and in some cases, just parents and coaches.
"Having greater certainty about who has and who hasn't suffered a brain injury is really important."
A concussion is a mild traumatic brain injury, often sustained in an accident or a sports-related collision.
Common symptoms include headaches, nausea, dizziness and confusion.
A single concussion can make a person more susceptible to further head injuries, which can lead to worse symptoms and other long-term health issues.
There is currently no global blood test to diagnose mild traumatic brain injuries, but Dr McDonald said the proposed tool would not replace other diagnostic measures like physical signs.
"The technology we're using is popping up in more research facilities and has been approved for other uses in clinical settings overseas," he said.
"That's the goal - to have it used acutely after injury so it can help confirm diagnosis and inform the patient journey."
The study from Monash University and The Alfred was published in the peer-reviewed Neurology journal on Wednesday.
The findings come after a new concussion-focused sports medicine hub was opened by Prime Minister Anthony Albanese last week.
The centre at the Collingwood Football Club's Melbourne headquarters will create tools to diagnose and manage concussion injuries.
Concussion has become a major issue for the AFL, with former players launching high-profile class actions and individual lawsuits in the Victorian courts.
Several deceased players have been diagnosed with the concussion-related condition, severe chronic traumatic encephalopathy.
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