What Is Possible With Blood Analysis?



Oct. 25, 2021 — Once valued at over $9 billion dollars, it seemed like Theranos was going to change the world of routine blood testing. Their claim was revolutionary: Using blood from a finger prick, they could run over 200 different tests. With a trip to a local pharmacy, someone could get testing done without getting blood drawn and receive the results in hours, rather than days. What’s more, Theranos said dozens of tests could be run on one drop of blood alone, and these tests would cost a fraction of traditional lab work.

But famously, Theranos’s house of cards came tumbling down. The microwave-sized machine that supposedly could run these tests, dubbed the “Edison,” simply did not work. What came as a shock for Silicon Valley and the investment world was no surprise to those in the blood testing industry.

“It was like saying you could build a flying car that is also a submarine, for the same price as an entry-level Toyota,” says Sheldon Campbell, MD, PhD, a professor of laboratory medicine at Yale School of Medicine.

Unlike the world of computing technology, where one breakthrough can revolutionize the entire field, progress in blood analysis is steadier and slower, like the automotive industry, Campbell says. While the automotive industry has developed hybrids and electric vehicles, the foundations of a car have remained the same.

“The drive trains haven’t changed, and the tires haven’t changed,” he says. “It’s pretty mature technology.”

Similarly, process in blood testing is evolutionary, rather than revolutionary.

When you get blood tests done, the technician uses a needle to draw blood from a vein in your arm into a blood collection tube. Each tube collects between 1/2 to 1 teaspoon of blood, and the technician will fill one to several tubes during the draw, depending on the number of tests your doctor ordered. This gives lab technicians plenty to work with, and doctors can even request additional tests after a sample is taken.

About half of blood is made up of red and white blood cells, while the other half is liquid. Most diagnostic tests use the liquid portion, meaning that only half of a standard sample is usually used for testing. You can also use blood from a finger prick, also known as a capillary sample, for testing, but it can be more difficult. These samples — a few drops of blood — are 30 to 100 times smaller than your standard blood draw. Unlike blood taken directly from a vein, capillary blood is mixed with liquid from tissues, which can contribute to an inaccurate result.

For simpler tests like checking glucose levels, something that people with diabetes do multiple times a day, using a small amount of blood from a finger works just fine. In fact, the most advanced glucose monitors can even produce accurate results with a fraction of the blood needed for a typical capillary sample.

“You’re literally able to take the capillary sample, place it on your test strip, put it into your device, and this simple one-step chemical reaction takes place in that testing chamber so that you can get a glucose measurement,” says Kimberly Sanford, MD, president of the American Society of Clinical Pathology.

But moving more complicated tests that require multiple chemical reactions out of central laboratories and into clinics gets trickier, Sanford says. Running multiple tests on a few drops of blood also adds additional engineering challenges, as a certain amount of blood is necessary for each result.

Diagnostic testing that occurs outside of the lab, also known as point-of-care testing, is also more expensive than testing done in a centralized lab. While these larger labs are built to manage multiple samples at one time, point-of-care testing is done one at a time.

To really get your bang for your buck, the tests need to be easy, fast, and, most importantly, accurate. Unless these in-office tests can provide clinicians with all the information they need to make a medical decision, it makes more sense to send off samples to a lab.

“No point of care test, however simple, is easier than checking off one more box on a lab order form,” Campbell says.

But despite these hurdles, bits and pieces of laboratory testing have been making their way to clinics and bedside care.

“They’re similar technologies to what we would use in the main laboratory on the larger analyzers, but they miniaturize them make them more portable,” says James H. Nichols, PhD, a professor of pathology, microbiology, and immunology at Vanderbilt University Medical Center in Nashville.

Advances in microfluidics — systems that process very small amounts of liquid for testing — have made it possible to run multiple diagnostic tests on a few drops of blood, just not as many as Theranos had promised.

Abbott Laboratory’s i-STAT, for example, a handheld blood analyzer with test-specific, single-use cartridges, can deliver multiple results from a standard finger-prick sample. Their Chem 8+ cartridge can deliver results for nine metabolic measures with a few drops of blood. To perform a test, the user places two or three drops of whole blood on the test cartridge, which is then inserted into the analyzer. A new test cartridge is used for each patient.

The i-STAT delivers lab-accurate testing for blood gases, electrolytes, chemistries, coagulation, hematology, glucose, and cardiac markers, an Abbott spokesperson says. Results are available in 2 minutes.

While the device was designed for urgent care settings, it is now also used at health fairs, medical tents at events, and many other mobile care settings, Nichols says.

A few tabletop blood chemistry analyzers that perform these same types of tests are also available for both emergency care as well as outpatient clinics. The Piccolo Xpress, for example, a portable analyzer roughly the size of a shoebox, can run up to 14 tests on a finger-prick sample of blood and deliver results in 12 minutes.

Complete blood counts, a common group of tests that count the number of white blood cells, red blood cells, and platelets in your blood, have also begun to make their way into primary care and other outpatient clinics, Nichols says. With a few drops of blood, a clinician can get results in 3 minutes or less.

Looking forward, “there’s also going to more infectious disease [testing] moving from the main laboratory and out into the community,” Nichols says, which in part has been driven by the importance of rapid COVID-19 testing. For example, developing additional rapid, easy-to-use tests for diseases more common outside of the United States, like malaria and dengue fever, could help improve access to laboratory diagnostics in developing countries, he says.

“It’s going to be an evolutionary process,” Campbell says, as bits and pieces of laboratory testing continue to be adapted to more rapid and portable technologies. “And it will work for both directions. The point-of-care market is clearly expanding, and people are coming up with clever ideas and ways of doing things at point-of-care, but the lab-based side won’t be static either,” he said. “They’ll sort of grow toward each other.”


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