Cell Count and Differential, Synovial FluidSynovial fluid
Performed by: Quest Diagnostics
What Is Synovial Fluid?
Synovial fluid is the thick liquid that lubricates your joints and keeps them moving smoothly. It’s on all of your joints, including in your knees, shoulders, hips, hands, and feet.
What Is a Synovial Fluid Analysis?
A synovial joint fluid analysis is a group of tests your doctor can use to diagnose problems with your joints.
Joint conditions like arthritis, gout, infections, and bleeding disorders can change how your synovial fluid looks and feels. A sample of this fluid taken during a procedure called an arthrocentesis can help your doctor figure out what’s causing your symptoms.
What’s The Purpose of a Synovial Fluid Analysis?
If you have joint symptoms like:
→ Fluid buildup
Synovial fluid analysis can also help your doctor figure out if you have:
→ A condition that inflames your joints, like gout, rheumatoid arthritis, and lupus
→ An infection like septic arthritis
→ Bleeding disorders like hemophilia or von Willebrand disease
→ A disease that break down joints over time, like osteoarthritis
Your doctor might also use this test to see if your treatment for your joint condition is working.
A synovial fluid analysis may be ordered to diagnose or rule out the following conditions:
→ Autoimmune disorders:
Autoimmune disorders are conditions in which a person’s immune system mistakenly attacks healthy tissue. In some autoimmune disorders, including rheumatoid arthritis, lupus, and psoriatic arthritis, the immune system damages healthy tissues of the joints.
→ Septic arthritis:
Septic arthritis is an infection caused by microbes such as bacteria or fungi that lead to acute inflammation in one or more joints.
→ Gout or pseudogout:
Gout and pseudogout are painful forms of arthritis, caused by the accumulation of uric acid or calcium crystals in the joint.
→ Bleeding in the joint:
Also called hemarthrosis, an accumulation of blood in the joint can be caused by an injury to the joint, cancer, hemophilia, and other health conditions.
Synovial fluid analysis is helpful for determining the underlying cause of arthritis, particularly for septic or crystal-induced arthritis. The white cell count, differential count, cultures, Gram stain, and crystal search using polarized light microscopy are the most useful studies.
Arthrocentesis with synovial fluid analysis should be attempted in all patients who have a joint effusion or signs suggestive of inflammation within the joint, without a known cause. The most important reason to perform a synovial fluid analysis may be to evaluate for septic arthritis in a patient presenting with an acutely swollen joint that is painful and warm even in patients with a known arthritic disease.
Synovial fluid analysis is also helpful in narrowing the differential diagnosis by distinguishing between categories of joint effusions (ie, inflammatory versus noninflammatory), and to diagnose hemarthrosis.
Biomarkers included in this panel:
Normal joints contain a small volume of synovial fluid that is highly viscous, clear, and essentially acellular. Clarity: Increased opacity of the fluid is usually due to abnormally large numbers of nucleated or red blood cells (RBCs). HoweveLearn more
Basophils are not a primary focus in synovial fluid analysis, and their presence in synovial fluid is typically not a key diagnostic marker for joint-related conditions. Instead, the analysis primarily concentrates on more common white blood cell typLearn more
Color and clarity may vary. Normal synovial fluid is clear and colorless or straw-colored. Abnormal fluid may look cloudy, opaque, and/or differently colored. For example, cloudy fluid may indicate an infection, and pink or reddish fluid may indLearn more
Crystals, Synovial Fluid
The presence and identification of crystals in synovial fluid analysis are essential for diagnosing specific joint-related conditions, particularly gout and CPPD disease. This diagnostic information informs appropriate treatment strategies to manageLearn more
The percentage of eosinophils in synovial fluid analysis is a valuable diagnostic marker that can indicate various joint conditions, particularly eosinophilic synovitis. It serves as a crucial piece of information for healthcare providers to determinLearn more
Lymphocytes are a type of white blood cell that plays a key role in the immune system. They are responsible for recognizing and combating infections, including viral and autoimmune diseases.Learn more
The percentage of monocytes and macrophages in synovial fluid analysis serves as an important indicator of joint inflammation and immune response. It aids in the diagnosis and management of various joint conditions, particularly those characterized bLearn more
Synovial fluid analysis includes a differential cell count, which identifies and quantifies the different types of white blood cells present in the fluid. Neutrophils are one of the cell types counted in this differential analysis. It is a critical pLearn more
Synoviocytes are essential for joint health and the production of synovial fluid, but their percentage is not a standard component of synovial fluid analysis. Instead, the focus of this analysis is on the presence and percentages of white blood cellsLearn more
Total Nucleated Cell Ct
The Total Nucleated Cell Count (TNCC) in a synovial fluid analysis helps to assess joint health by quantifying the number of white blood cells in the synovial fluid. An elevated TNCC can indicate joint inflammation, infection, or crystal-induced arthLearn more