The Expert Series: Lupus Lab Tests and Blood Work

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The following transcript is automatically generated and may contain typos or misspellings. Please listen to the episode for the most accurate language.

Host 0:00
Welcome to The Expert Series brought to you by the Lupus Foundation of America. Our speaker today is Dr. Christine Lee, who's a member of the clinical teaching faculty and an attending physician at Cedar Sinai Medical Center. Today, Dr. Lee will be speaking about lupus lab tests and blood work. I'd like to turn it over to Dr. Lee, and thank you for joining us.

Dr. Lee 0:22
Great, thank you. So today we'll be discussing lab tests and lupus. Topics of discussion will include difficulty of diagnosis, antibodies, and their significance or lack thereof, testing prognosis and other useful diagnostic tools.

Patients report waiting nearly six years from onset of symptoms before receiving an accurate diagnosis of lupus. There seems to be a diagnosis disconnect in which patients report nearly six years to obtain a correct lupus diagnosis and seeing four different physicians, whereas rheumatologists report being able to diagnose a patient with lupus in two to three visits. 60% of patients report being initially misdiagnosed.

So what makes diagnosing lupus so challenging? 52% of patients report that they minimize their symptoms when talking to physicians, while 72% of physicians are unaware that patients tend to under report their symptoms. In addition, symptoms and antibodies evolve over time. No single biomarker has adequate performance. And anti dsDNA is only about 33% positive in many studies. There's also many unreliable or inconsistent lab results using different forms of testing, including the Eliza and multiplex.

So timely and accurate diagnosis affects costs and clinical outcomes. Reviewing the American College of Rheumatology criteria for classification of lupus, this includes not only clinical criteria, but the lab criteria as well. I'll run over the clinical really quickly, which includes skin criteria including butterfly or discoid, rashes, Sun sensitivity and oral or ulcers, as well as systemic criteria, which includes arthritis, serositus, kidney disorders and neurological disorders. Lab findings include blood abnormalities such as immunologic disorders, including the presence of anti phospholipid, antibodies, lupus anticoagulant, anti dsDNA, anti Smith, and false positive syphilis tests. A positive ANA is also listed as one of the criteria and one needs four out of 11 of this combined clinical and laboratory criteria for lupus.

So no single test can determine whether a person has lupus but like the tests that I mentioned before they can help make a diagnosis. Not only do we look at antibodies, sometimes we do skin biopsies or kidney biopsies as well. An ANA test which is an anti nuclear antibody is the umbrella antibody for auto immune disease. Typically, we check this by looking at human epithelial cells, a Lupus patients blood is added and if antibodies are present in the blood, they're identified by tagging with an immuno fluorescent material and detected by a fluorescent microscope. So the sensitivity of the ANA is quite high for lupus over 95% of lupus patients are positive. So if you have a negative ANA a lupus diagnosis is unlikely. There are many false positives so an ANA is not specific, and you can see it turn positive and other diseases such as rheumatoid arthritis or chronic infections. Again, a positive ANA doesn't confirm diagnosis of lupus, you need other criteria as well. Looking into more specific antibodies to anti dsDNA, which is positive about 60% of lupus patients, this is highly specific. And we see that it does tend to fluctuate with disease activity and it's also found in active lupus nephritis patients therefore, we often use this as a disease activity monitoring marker. The anti Smith antibody is also very specific for lupus as well, and it's present in 10 to 30% of lupus patients. Anti phospholipid antibodies which include the lupus anticoagulant, anti cardio life and antibody and anti-beta-2 glycoprotein antibody are also very helpful for helping us figure out if a patient has lupus or not. These are associated with clotting disorders, such as blood clots in the arteries or veins as well as frequent miscarriages. Other blood abnormalities we look at include the blood count as inpatients may have anemia, or decreased platelets or decreased white cells.

Other labs that we look at include in a general screening for patients a complete blood count urine analysis, blood chemistries, inflammation markers, including an ESR, which is a sedimentation rate as well as CRP, which is a C reactive protein. We look at complement levels as well. And often times, X rays or imaging tests of affected organs are helpful. We also look at echocardiograms to see if there's any involvement in the heart depending on the patient. And often times, electrical studies such as EEGs, or EMGs, which are neurological studies to look at whether a person has neuropathy or seizures can be helpful in determining the diagnosis of lupus.

Now, in conclusion, Lupus is a heterogeneous disease that's not defined by a concrete set of laboratory markers. Rather, it takes a combination of antibody testing symptoms and exam findings to make a swift and accurate diagnosis. Now, while auto antibodies can predate the onset of disease, it's generally not recommended to conduct ANA screenings in the general population. Therefore, with the right clinical suspicion, one should check an ANA. But it's important to remember that the diagnosis of lupus includes much more than simply an ANA or just laboratory findings. It's important to look at each individual loan and also clinical findings. Thank you.

Host 6:45
Thank you, Dr. Lee for joining us today. We appreciate all of the great information that you shared about lupus lab tests and bloodwork.

For those listening in we invite you to check out additional segments of The Expert Series at lupus.org. If you'd like to learn more about living well with lupus, you can find additional resources on the National Resource Center on Lupus, or you can call one of our health educators at 1-800-558-0121. If you would like to connect with others who are impacted by lupus, check out our online community, LupusConnect, where you can talk with others find emotional support, and discuss practical insights for coping with the daily challenges of lupus. Thank you and have a wonderful day.

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