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Is There Anything New Blood Tests Can’t Diagnose?

“Precision pathology” will add higher quality lab tests to predict treatment outcomes for ailments ranging from concussions to heart attacks.

blood test diagnosis

The right diagnosis means everything.

In some cases, it can be a matter of life and death.

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A recent study in the Journal of Evaluation in Clinical Practice found that more than 20 percent of patients who went for a second opinion at the Mayo Clinic had, in fact, been misdiagnosed by their primary care doctors.

Doctors are human and ailments are complex, so misdiagnoses are nothing new.

What can prevent patients from being inaccurately diagnosed?

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Read more: New blood test may pinpoint cancer tumors »

Accuracy of new blood tests

One tool is a blood test.

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There’s not always been a test for everything out there.

However, there are a few new pathology exams (and more on the horizon) that can help doctors better detect diseases and conditions.

Here are three recent developments:

Viral vs. bacterial infections: Wouldn’t it be great to know if you really need an antibiotic or if you should just let a cold run its course?

A Duke University team is looking into the efficacy of a test that could distinguish viral from bacterial infections.

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Dr. Geoffrey S. Ginsburg previously told Healthline that he would love to have the “pregnancy test equivalent to viral infections.”

Heart attack: Researchers at King's College London created a blood test that better detects heart muscle damage due to a heart attack.

When a doctor suspects that a patient has had an attack, only some incidents show changes on a heart trace or ECG. Those exams test levels of cardiac troponin, which is a protein released by the heart that is common after heart attacks or inflammation. When doctors can’t find cardiac troponin in the blood, patients are labeled as low-risk and typically discharged.

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Researchers, however, looked at 4,000 patients and found that 47 percent of those actually had an intermediate risk and required more tests. Their test for myosin-binding protein C is a better indicator of how much heart muscle has been damaged.

Dr. Tom Kaier, a cardiologist with Kings College London, told Healthline that the myosin-binding protein C is present in greater abundance and may rise quicker than troponin after a heart attack. That could change the way heart attacks are diagnosed.

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“Troponin is an excellent test, but it has its limitations. It takes over three hours to appear in adequate levels in the bloodstream to be measured reliably,” Kaier noted.

Considering that only 14 to 17 percent of patients that go to emergency rooms with chest pain have a heart attack, the other 80 percent want reassurance as soon as possible. A quicker diagnosis may also improve patient outcomes.

The detection of myosin-binding protein C “appears in the circulation quicker, and thus could rule out heart attacks in more patients at an earlier time point than currently possible,” Kaier added.

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Concussions/traumatic brain injuries: Accurately diagnosing a concussion or traumatic brain injury can be a bit of a guessing game when it comes to specifying the severity of the impairment.

But Dr. Linda Papa, an emergency medicine physician and researcher at Orlando Health released a study in JAMA Neurology detailing a blood test that measures a protein released by brain cells upon an injury.

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More of the protein indicates a higher severity of brain injury, she explained.

Symptoms of a brain injury can be subtle and may not come on for several days. She told Healthline that diagnosing a concussion can be “very subjective” and is “often based on the experience of the clinician.”

If a person doesn’t see a brain expert, they may not be accurately diagnosed, so having a concrete test to confirm injury would be a big step. A CAT scan can give an assessment of a brain injury, but it only detects lesions and cannot detect all of them.

Having a definitive blood test could help doctors make better treatment decisions sooner —hopefully leading to better patient outcomes, Papa said.

If approved by the Food and Drug Administration (FDA), Papa’s test would be the first of its kind.

“We’re just a couple of years from it being available,” she added. “We’re hoping the blood test will find injury where it couldn’t be seen before.”

Papa noted that it was also tested in patients of all ages with severe traumatic brain injury and seems to “cover the spectrum” of brain injuries.

Read more: High-tech blood test may detect cancer early »

The future of precision pathology

Dr. Michael J. Donovan, a pathologist and researcher at The Mount Sinai Hospital in New York, said there are many new innovations happening with blood tests.

There are also developments in tests to evaluate urine, saliva, and cerebrospinal fluid.

In the oncology field, for instance, researchers are looking at cell-free DNA, which is the deoxyribonucleic acid (DNA) in blood that can be isolated and sequenced to identify cancer-related genes with mutations in them.

Doctors then can tell if a cancer drug will work on the patient. The blood acts as a companion diagnostic to gauge the efficacy of a drug before it’s even given.

“That’s one of the very practical ways in which the field has advanced,” Donovan told Healthline.

Other blood test innovations include evaluations that can predict how a kidney transplant patient will respond. This can replace an invasive biopsy. Researchers are also targeting urine tests in this area.

Donovan said that blood tests in the future may also be able to determine if a patient is building a response to human papillomavirus (HPV) in a lesion instead of having to biopsy it or conduct an intrusive cell scraping.

Blood tests are also a pathway to evaluate the possibility of neurodegenerative diseases such as Alzheimer’s disease.

“We’re always looking for ways to detect the manifestation of Alzheimer’s prior to actual clinical manifestations,” Donovan said.

Other liquid biopsy options could evaluate a patient’s immune system via bloodwork so doctors can monitor an individual’s state via a simple blood draw.

Assessing DNA isn’t the only research pathway, either, as researchers are looking to evaluate peptide fragments in the blood. Peptides are amino acids that are linked via peptide bonds and in some ways are similar to DNA and ribonucleic acid (RNA).

DNA gives a blueprint of genes, while RNA helps to execute the DNA’s guidelines.

Donovan said that the field of liquid biopsies will continue to evolve — again, not just via bloodwork but through spinal fluid, saliva, and urine. That will give doctors multiple tools to better diagnose patients and hopefully improve outcomes.

“What we see in blood under a microscope, that will pull together a more comprehensive genotype of a person,” Donovan said.

“That’s the future of precision pathology,” Donovan added.

Read more: New blood test can identify every virus you’ve ever had »

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