CB-CAPs: 2 Biomarkers For Diagnosing Lupus

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Diagnosing lupus is a challenge. But, new biomarkers known as CB-CAPS can improve lupus detection by 48%.

Lupus symptoms are often confused with those of other conditions. This causes many people to be misdiagnosed and even prescribed inappropriate medications.

An inaccurate diagnosis can allow lupus to go unchecked. This can lead to permanent tissue damage. Or, when inappropriate medications are used, it is possible for a person to develop drug-induced lupus (DIL).

According to a survey done by the Lupus Foundation of America, it takes an average of 6 years and 4 specialist referrals to be correctly diagnosed with lupus.

With so much at stake, it is important to take an active role in tracking and reporting symptoms to your doctors. By staying up-to-date on the newest laboratory tests, you can also be aware of new biomarkers that may be evident in bloodwork.


Over 60% of patients who eventually developed lupus will have had abnormal biomarker levels at least 5 years prior to being diagnosed, according to a study. Because of this, lab results are crucial for the timely diagnosis of lupus and other connective tissue diseases.

Lab tests like antinuclear antibody (ANA) test, anti-double stranded DNA (anti-dsDNA), anti-smith and complement proteins (C3/C4) are considered standard of care tests. However, these tests do not always present a consistent, accurate picture. Forty to ninety percent of people diagnosed with lupus will test negative on anti-dsDNA and anti-smith tests. When a test fails to identify a condition when it is present in a person, it is known as a false negative.

On the other hand, a screening test like the ANA test is likely to be positive even when a person does not have lupus. It is estimated that over 32 million Americans have a positive ANA. That is almost 14% of the US population. But, they do not all have lupus.


Cell-Bound Complement Activation Products (CB-CAPs)

Researchers have discovered a way to help overcome some of these challenges using two novel lupus biomarkers called Cell-Bound Complement Activation Products (CB-CAPs). These biomarkers are unique because they look for evidence that the classical complement pathway has been activated. The classical complement pathway is associated with the complement system which helps the body remove microbes and damaged cells with inflammation caused by lupus.

CB-CAPs are believed to be like a fingerprint left behind by the lupus diseases activity process and have been shown to outperform traditional lupus biomarkers alone.


Effectiveness of CB-CAPs in lupus diagnosis

A 2014 study suggests that CB-CAPs can improve detection of lupus by 48% compared to standard-of-care anti-dsDNA alone. The researchers also found that CB-CAPs outperformed C3/C4 tests and isolated ANA testing. Because of this, the addition of CB-CAPs testing may help diagnose people that would have otherwise been missed by traditional testing.

Advanced lupus diagnostic tests containing CB-CAPs were first introduced in 2012 and are now available at academic medical centers as well as at advanced rheumatology care centers across the United States.


CB-CAPs in context

Although lab tests are far from perfect, the discovery of CB-CAPs shows that researchers are headed in the right direction. Early and accurate diagnosis is an important part of the battle against lupus.

Being misdiagnosed and waiting years before learning the reason for symptoms can be frustrating and isolating. If you have concerns about the diagnostic process, speak with your doctor about advanced lupus testing from rheumatology focused laboratories.

To learn more about innovations in lupus diagnostic testing and other tests that can help in the health care journey visit www.exagen.com/patient-info.

Comments (1)

One thought on “CB-CAPs: 2 Biomarkers For Diagnosing Lupus

  1. This is great. One doctor said I have lupus and another said I didnt. and ye all the symptoms were there. I cant wait to have her run the test again with the new labs avalable.

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