Castleman Disease Blood Test

What is Castleman Disease?

Castleman Disease is a rare disorder affecting the lymph nodes and related tissues, characterized by abnormal lymph node enlargement. It is caused by overproduction of Interleukin-6 (IL-6), a key inflammatory protein that leads to systemic inflammation and multi-organ dysfunction. The Interleukin-6 (IL-6), Serum test is the most important test for monitoring Castleman Disease activity and treatment response.

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What causes Castleman Disease?

Castleman Disease is caused by overproduction of Interleukin-6 (IL-6), an inflammatory signaling protein that normally helps coordinate immune responses. In Castleman Disease, excessive IL-6 triggers uncontrolled growth of lymph node cells and causes widespread inflammation throughout the body. The exact trigger for IL-6 overproduction varies by type, with the multicentric form sometimes linked to human herpesvirus-8 (HHV-8) infection, especially in people with weakened immune systems, while the unicentric form has no clear infectious cause.

What is the best test for Castleman Disease?

The Interleukin-6 (IL-6), Serum test is the most important blood test for Castleman Disease because it directly measures the inflammatory protein driving the condition. Elevated IL-6 levels indicate active disease and help doctors assess severity, monitor how well treatments are working, and predict potential complications affecting multiple organs. While tissue biopsy and imaging studies are required for initial diagnosis, the IL-6 test provides crucial ongoing monitoring data. Regular IL-6 testing helps your healthcare team make informed decisions about treatment adjustments and catch disease flares early before serious complications develop.

When should I get tested for Castleman Disease?

You should get tested if you have persistent swollen lymph nodes that do not go away after several weeks, especially when accompanied by unexplained fevers, night sweats, fatigue, or unintended weight loss. Testing is also important if you experience enlarged liver or spleen, shortness of breath, or fluid buildup in your abdomen or legs. If you have already been diagnosed with Castleman Disease, regular IL-6 testing helps monitor disease activity and treatment effectiveness, typically every few months or as recommended by your healthcare provider.

What are the symptoms of Castleman Disease?
Symptoms vary depending on whether you have unicentric (single lymph node area) or multicentric (multiple areas) Castleman Disease. Unicentric disease may cause a painless lump in your neck, chest, or abdomen with few other symptoms. Multicentric disease typically causes more widespread symptoms including persistent fever, drenching night sweats, severe fatigue, loss of appetite and weight loss, enlarged lymph nodes in multiple areas, enlarged liver and spleen, skin rashes, and numbness or weakness in hands and feet. Some people also experience fluid retention causing swelling in legs or abdomen.
Who is at risk for Castleman Disease?
Castleman Disease can affect anyone, but certain factors increase risk. The condition most commonly appears in young adults between ages 20-40, though it can occur at any age. People with HIV infection or weakened immune systems have higher risk of developing the multicentric form, particularly when infected with human herpesvirus-8 (HHV-8). The disease affects men and women roughly equally. Unlike many conditions, there is no clear genetic pattern or family history component, and lifestyle factors do not appear to influence risk. The unicentric form occurs randomly without identifiable risk factors.
What happens if Castleman Disease is left untreated?
Untreated Castleman Disease can lead to serious complications, especially the multicentric form. Persistent high IL-6 levels cause progressive organ damage including kidney failure, liver dysfunction, and heart problems. The uncontrolled inflammation can trigger life-threatening infections due to immune system dysfunction, severe anemia requiring blood transfusions, and dangerous fluid accumulation in the lungs or abdomen. People with multicentric Castleman Disease also have increased risk of developing lymphoma and other cancers. Even the unicentric form, while less aggressive, can cause compression of nearby organs and blood vessels if the enlarged lymph node grows large enough, making early detection and monitoring critical.
Can Castleman Disease be diagnosed with a blood test?
Blood tests alone cannot diagnose Castleman Disease, but they play an essential role in the diagnostic process and ongoing monitoring. Definitive diagnosis requires tissue biopsy showing characteristic abnormal lymph node architecture and imaging studies to determine if the disease is unicentric or multicentric. However, the Interleukin-6 (IL-6), Serum test provides crucial supporting evidence by measuring the inflammatory protein driving the condition. Other blood tests typically show abnormalities like anemia, elevated inflammatory markers, and abnormal protein levels. Once diagnosed, regular IL-6 blood testing becomes invaluable for monitoring disease activity and treatment response.
How is Castleman Disease treated?
Treatment depends on whether you have unicentric or multicentric disease. Unicentric Castleman Disease is often cured with surgical removal of the affected lymph node, with most people experiencing complete recovery. Multicentric disease requires ongoing medical management including siltuximab, a medication that blocks IL-6 and reduces inflammation, rituximab for cases associated with HHV-8 infection, chemotherapy for aggressive disease, and corticosteroids to control inflammation. Antiviral medications may help if HIV or HHV-8 infection is present. Your treatment plan is individualized based on disease severity, symptoms, and how well you respond to therapy, with regular blood tests monitoring treatment effectiveness.
How can I prevent Castleman Disease?
There is no known way to prevent Castleman Disease because the exact causes are not fully understood, and the unicentric form appears to occur randomly. However, you can reduce risk of the multicentric form by managing factors related to immune function. If you have HIV, maintaining good control with antiretroviral therapy significantly reduces risk of developing HHV-8-associated Castleman Disease. Practicing safe sex and avoiding sharing needles prevents HIV and HHV-8 transmission. For people already diagnosed, working closely with your healthcare team, attending regular monitoring appointments, and promptly reporting new symptoms can help catch disease progression early and prevent serious complications.
What can I do at home for Castleman Disease?
While medical treatment is essential, several home strategies support overall health and well-being with Castleman Disease. Prioritize rest and sleep to help your body manage inflammation and fatigue. Eat a balanced diet rich in protein, fruits, and vegetables to support immune function and maintain strength, especially if you experience weight loss. Stay well-hydrated to help your kidneys process medications and manage fever. Gentle exercise like walking or yoga helps maintain energy and mood when you feel up to it. Monitor and record your symptoms including fever patterns, lymph node changes, and new concerns to share with your healthcare provider. Practice good hygiene to reduce infection risk, and consider joining support groups to connect with others managing rare diseases.
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Interleukin-6 (IL-6), Serum
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What's included
Fast & easy, results by email & SMS
No need to visit a doctor
Private & confidential
No insurance needed
Results explained
No extra fees paid at the lab

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