Featured Bio -
May 10, 2021

Why is Lupus so Hard to Diagnose?

Juana Mata’s symptoms started with joint pain that came and went. Then she noticed a rash on her face. When she started getting ulcers in her mouth and nose a few months later, she went to urgent care.

“I told the urgent care doctor about the mouth ulcers and the pain and joint aches, and he said I looked fine,” she says. “I asked if he could do blood work because I just knew something was wrong.”

She was right: Her blood tests showed dangerously low platelets, which put her at high risk for internal bleeding.

“I was admitted to the ICU that night,” she says. “And the doctor told me I have lupus.”

Jeff Carlin
Most lupus diagnoses don’t happen in the ICU. But Juana’s experience of having several different symptoms long before getting a diagnosis is all too common for people with lupus. We recently talked to BRI researcher Jeffrey Carlin, MD, who was a rheumatologist for three decades, about how lupus is diagnosed and why it’s so complicated.

What is lupus?

Lupus is an autoimmune disease, a condition where your body’s immune system mistakenly attacks healthy tissues. Lupus can affect different parts of the body including the skin, joints, kidneys and blood cells.

What causes lupus? Why do people get lupus?

Scientists don’t know what causes lupus, but researchers like those at BRI are working to find out. We do know that there is a genetic component to lupus, and if you have a family member with the disease or another autoimmune disease, you may be more likely to get it.

How does a doctor diagnose lupus?

Doctors diagnose lupus based on criteria from the American College of Rheumatology. Those criteria include joint pain, rashes, mouth sores, sun sensitive skin eruptions, worsening disease symptoms after sun exposure and a positive antinuclear antibodies (ANA) test. This test identifies antibodies that attack healthy cells in your body.  Patients get a certain number of points for each criteria. Diagnoses require ten points and a positive ANA test. 

“So joint pain may be X number of points, kidney failure would be significantly more,” Dr. Carlin says.

People can also have “incomplete lupus” where they meet some but not all criteria. Others still may have “preclinical” lupus, where they experience early symptoms of the condition and may go on to develop lupus.

“With preclinical lupus, I’ll often tell patients that they have about a 50 percent chance of developing lupus and ask them if they would like to start treatment,” Dr. Carlin says. “We typically use very mild therapies that you take without significant long-term side effects. And patients who start treatment sooner typically have better outcomes.”

Why does it take so long to diagnose lupus?

Lupus can take a long time to diagnose for a number of reasons: Some patients experience symptoms that come and go. Others might have a slow progression, where they first experience one symptom and others develop over time.

“I remember one patient saying she had low platelet counts in college when she came in to see me with chest inflammation 20 years later,” Dr. Carlin says. “We repeated her blood work and her blood tests were classical for lupus — but she was fine for 20 years and it took that long for her to meet the criteria.”

The many different ways lupus can manifest can also lead to slower diagnoses.

“Presenting with the rash and joint pain is somewhat standard,” Dr. Carlin says. “But we call lupus ‘the great masquerader’ — no two cases are alike.”

We call lupus 'the great masquerader' - no two cases are alike.
Dr. Jeffrey Carlin

What is usually the first sign of lupus?

For most people, the first sign of lupus is joint pain or a rash.

“That’s the case for about 90 percent of people,” Dr. Carlin says. “Occasionally, somebody will present with kidney disease or low platelet counts. But for most people, the rash and painful joints will drive them to the doctor. Then the blood samples are drawn and the rest is history.”

Can lupus be misdiagnosed? Does a positive ANA test mean I have lupus?

Yes, lupus can be misdiagnosed. Dr. Carlin explained that doctors who aren’t familiar with lupus might assume that because someone has a positive ANA test, they have lupus.

“But when that patient finally makes it to a rheumatologist, they find out they really have fibromyalgia and not lupus,” Dr. Carlin says.

An ANA test is a crucial piece of diagnosing lupus. But up to 25 percent of women can have a positive ANA test depending on their age. Other autoimmune conditions like Hashimoto’s disease can also lead to a positive ANA test.

“A positive ANA doesn't mean you have lupus, but a negative one rules it out,” Dr. Carlin says.

Can getting a diagnosis sooner impact lupus care and outcomes?

Dr. Carlin says yes. He believes in early intervention and aims to start treating patients as soon as possible. He’ll often talk to patients who don’t meet the full criteria for lupus diagnosis about potential treatments that could help keep the disease from progressing.

“Starting treatment can alter the natural history of the disease,” Dr. Carlin says. “So if we can get somebody on even mild treatment, like Plaquenil, it can bend the arc. So those people may not have as serious disease as people who start treatment later.”

How is BRI working to improve lupus treatment and care?

BRI scientists lead clinical trials and lab research to inform lupus treatment and care. Much of this research starts with blood samples that people with lupus donate to our biorepository.

“Our robust biorepository with samples from over 700 people enables us to study the genes that contribute to lupus and the basic immunology of the disease,” Dr. Carlin says. “This could help understand what causes lupus, and how we can better treat it — or prevent it all together.” 

Learn more and get involved

Eleven years after her diagnosis, Juana is doing well and spends much of her time advocating for people with lupus. Inspired to build a supportive community, she started Looms4Lupus, which offers support groups and resources for people with lupus and fibromyalgia in English and Spanish.

“My hope for the future is that research will lead to better treatments that will help us have a better quality of life and not have to worry about organ damage,” Juana says. “Or to find a cure for lupus. That would be the best thing.”

If you’re interested in learning more about lupus research at BRI, read about research into the genes behind lupus and how the condition impacts three generations of one family. Those who are interested in participating in research and live in and around Seattle with lupus can get involved in our biorepositories. Supporters in Seattle and beyond can sign up for one of BRI's virtual Inside Immunology events, where our scientists give updates about the latest research on lupus and many other diseases.

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