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Auto-antibodies

Understanding the Lupus and MCTD Connection

May 26, 2025 ·

Learn the key differences between lupus and MCTD, from Raynaud’s phenomenon to the RNP antibody, and why the distinction matters.

When you’re living with lupus, it can feel like every symptom and test is part of the same story. But what happens when new clues emerge, pointing toward a different diagnosis like Mixed Connective Tissue Disorder (MCTD)? Let’s break down the differences, key markers, and why it all matters for your care.

Read more: Understanding the Lupus and MCTD Connection

What Are Lupus and MCTD?

Lupus and MCTD are both systemic autoimmune diseases that cause inflammation throughout the body. They share overlapping symptoms like fatigue, joint pain, rashes, and even a positive ANA (antinuclear antibody) test.

MCTD, however, is what rheumatologists call an “overlap condition.” This means it combines features of lupus, scleroderma, and myositis, creating its own distinct condition. The trick is spotting the subtle differences that suggest it’s not “just lupus.”

Raynaud’s Phenomenon: A Clue to Look Deeper

Raynaud’s phenomenon—where fingers or toes turn white, blue, then red in response to cold or stress—is common in lupus. But when combined with other signs like skin tightening, it raises a red flag for MCTD.

Raynaud’s is also associated with scleroderma, a condition that’s part of the MCTD overlap. If you notice color changes in your fingers or toes, don’t dismiss it as “normal.” It might be a critical clue.

The Role of the RNP Antibody

If your doctor is digging deeper into an autoimmune diagnosis, they’ll often check your antibodies. One of the most important markers for MCTD is the RNP antibody, also called Sm/RNP or U1RNP.

A high RNP antibody level is like a neon sign pointing to MCTD. While lupus can sometimes present with this antibody, its strong presence should encourage doctors to evaluate for features of MCTD like muscle inflammation or fibrosis.

Muscle Inflammation and Skin Tightening

Symptoms like muscle weakness—difficulty combing your hair or climbing stairs—are more common in MCTD. This weakness stems from inflammation in the muscles, something not typically seen in lupus.

Skin tightening is another key difference. If you notice the skin around your fingers, hands, or forearms feels tighter or looks shiny, it’s worth mentioning. These changes point to the scleroderma component of MCTD and are rarely seen in lupus alone.

Why Diagnosis Matters

You might wonder: if the treatments for lupus and MCTD overlap, why does the distinction matter? The answer lies in the complications.

MCTD carries a higher risk of fibrosis—thickening and scarring—in the lungs or esophagus. These complications require different monitoring and treatment strategies than lupus. Knowing you have MCTD allows your doctor to anticipate and manage these risks early.

What Can You Do?

Autoimmune diseases are dynamic, and symptoms can evolve over time. If you’ve been diagnosed with lupus but notice new symptoms like Raynaud’s, muscle weakness, or skin tightening, don’t assume they’re part of the same story.

Discuss your concerns with your doctor and ask about the RNP antibody. It’s a small step that could lead to big insights into your health.

Dr. Elizabeth Ortiz, double board certified Rheumatologist

Retesting the ANA or Rheumatoid Factor

March 18, 2025 ·

knowing when to repeat your ANA and RF can help you make an autoimmune diagnosis

Blood tests like the ANA (antinuclear antibody) and rheumatoid factor (RF) are often the first steps when a doctor suspects an autoimmune condition like lupus or rheumatoid arthritis. But what happens when these tests come back negative, and your symptoms persist? Or when they’re positive but don’t seem to tell the full story? Let’s break down when retesting might make sense and how these tests fit into the bigger picture of autoimmune disease management.

[Read more…] about Retesting the ANA or Rheumatoid Factor

Can you have ANA negative lupus?

March 10, 2025 ·

if your ANA is negative, it can difficult to know if you have systemic lupus erythematosus (SLE)

Getting an autoimmune diagnosis like lupus is a life-changing event. But what we don’t talk about enough is how life-changing the journey to that diagnosis can be. For many, it’s a rollercoaster of confusing symptoms, endless doctor visits, and—often—conflicting test results. One of the most common points of confusion? The ANA test, its results, and what they actually mean when you’re trying to figure out if you have lupus.

Let’s dive into the complexities of the ANA test, what it means for lupus, and why focusing on your symptoms might be the key to getting the answers you need.

[Read more…] about Can you have ANA negative lupus?

Positive ANA Test: Lupus Symptoms & Next Steps

December 16, 2024 ·

Not all joint pain, rash and ANA mean lupus

If you’ve recently had an ANA (antinuclear antibody) test and are feeling a bit overwhelmed, you’re not alone. A positive ANA result can stir up a lot of questions and worries, especially when it comes to conditions like lupus. 

What Does a Positive ANA Mean?

Just because your ANA test came back positive doesn’t automatically mean you have lupus. The ANA test is a tool that helps us understand more about your immune system, but it’s only one piece of the puzzle.

[Read more…] about Positive ANA Test: Lupus Symptoms & Next Steps

HLA-B27: What It Means for Ankylosing Spondylitis and Arthritis

December 9, 2024 ·

The HLAB27 genetic test can be used to confirm a diagnosis of Ankylosing Spondylitis

If you’ve recently heard about the HLA-B27 test or had it done, you might be wondering what it really means for your health. It’s one of the many autoimmune tests that can be confusing—especially when you get a positive result and then hear your doctor say, “Oh, that doesn’t mean anything.” So, what exactly is HLA-B27, and why does it matter when it comes to arthritis and conditions like Ankylosing Spondylitis?

What Is HLA-B27?

HLA-B27 is a gene that produces proteins involved in your immune system. These proteins play a key role in helping your immune cells communicate with each other, which is crucial for maintaining a healthy immune response. Now, HLA-B27 is not the only gene involved in building a healthy immune system, but it has caught a lot of attention because of its connection to certain types of arthritis, especially Ankylosing Spondylitis.

[Read more…] about HLA-B27: What It Means for Ankylosing Spondylitis and Arthritis
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