URINALYSIS AND BODY FLUIDS (SYNOVIAL FLUID) LECTURE ONE

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URINALYSIS AND BODY FLUIDS (SYNOVIAL
FLUID)LECTURE ONE

• Dr. Essam H. Jiffri

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Synovial Fluid

• Synovial fluid, referred to as "joint fluid" is a
  viscous liquid found in the joint cavities.

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Synovial Fluid

• - It is formed as an ultrafiltrate of the plasma
  across the synovial membrane, which
  mucopolysaccharide containing hyaluronic acid and
  a small amount of protein is secreted by the
  cells of the synovial membrane.

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Synovial Fluid

• Except for high-molecular weight proteins, the
  plasma filtration is nonselective therefore,
  normal synovial fluid has essentially the same
  chemical composition as the plasma.
• - Synovial fluid supplies nutrients to the
  cartilage and acts as a lubricant to the surfaces
  of the frequently moving joints.

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COLLECTION

• The fluid is found in all joints, the specimen
  usually received in the laboratory is an aspirate
  of the knee.
• Synovial fluid is collected by needle aspiration,
  called arthrocentesis.
• - The normal amount of fluid contained in the
  knee cavity is less than 3.5 ml, this amount
  increases in disorders of the joints.

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COLLECTION

• Normal synovial fluid will not clot however,
  fluid from a diseased joint may contain
  fibrinogen and form a clot.
• - Recommended specimen containers include
• Ethylene diamine tetraacetic acid (EDTA) tube for
  cell counts and differentials.
• Heparinized tube for chemical and immunologic
  tests. Fluid for complement studies should be
  frozen before storage.
• Plain, sterile tube for microbiologic testing and
  crystal examination.

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COLLECTION

• - Analysis of synovial fluid is used to classify
  joint disorders in terms of their pathologic
  origins.
• - Five commonly used categories associated with
  fluid buildup and arthritis and their clinical
  significance are

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Clinical and Pathologic Significant of Joint
Disorders

• _________________________________________________
• Group Classification Pathologic Significance
• _________________________________________________
• I. Noninflamatory Degenerative joint
  disorders
• II. Inflammatory Immunologic problems,
  including
• rheumatoid arthritis and lupus
  erythematosus
• III. Septic Microbial infection
• IV. Crystal-induced Gout
• Pseudogout
• V. Hemorrhagic Traumatic injury
• Coagulation deficiencies

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COLLECTION

• - Results from both synovial fluid and blood
  analyses must be considered along with the
  patient's clinical history before a category is
  assigned.

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SYNOVIAL FLUID IN THE CHEMISTRY LABORATORY

• - Because synovial fluid is chemically an
  ultrafiltrate of plasma, chemistry test values
  are approximately the same as serum values, few
  chemistry tests are considered clinically
  important.

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SYNOVIAL FLUID IN THE CHEMISTRY LABORATORY

• - Normal synovial fluid glucose should not be
  more than 10 mg per dl lower than the blood
  value.
• - Synovial fluid lactate levels below 7.5 mmol/L
  provide a 98 percent for septic arthritis
  whereas levels above 7.5 mmol/L are found
  consistently with septic arthritis but may also
  be seen in rheumatoid arthritis.

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SYNOVIAL FLUID IN THE CHEMISTRY LABORATORY

• - Other chemistry tests that may be requested are
  the total protein and uric acid determinations.
• - Because the large protein molecules are not
  filtered through the synovial membranes, normal
  synovial fluid contains less than 3 g/dl of
  protein.
• - Increased levels are found in inflammatory and
  hemorrhagic disorders.

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SYNOVIAL FLUID IN THE CHEMISTRY LABORATORY

• - The elevation of serum uric acid in cases of
  gout is well known therefore, demonstration of
  an elevated synovial fluid uric acid may be used
  to confirm the diagnosis.

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SYNOVIAL FLUID IN THE SEROLOGY LABORATORY

• - Serology laboratory plays an important role in
  the diagnosis of joint disorders.
• - The majority of the tests are performed on
  serum, with actual analysis of the synovial fluid
  serving as confirmatory measure in cases that are
  difficult to diagnose.

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SYNOVIAL FLUID IN THE SEROLOGY LABORATORY

• - The autoimmune diseases rheumatoid arthritis
  and lupus erythematosus cause very serious
  inflammation of the joints and are diagnosed in
  the serology laboratory by demonstrating the
  presence of their particular autoantibodies in
  the patient's serum.

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SYNOVIAL FLUID IN THE SEROLOGY LABORATORY

• - Determination of synovial fluid complement
  levels can be an aid in the differential
  diagnosis of arthritis as to immunologic and
  non-immunologic origin.
• - Measurement of the complement components Clq,
  C4, C2, and C3 is performed primarily by single
  radial immunodiffusion.