Tests for arthritis/autoimmune diseases Flashcards
an immunoglobulin that is ABNORMALLY directed against IgG antibodies
rheumatoid factor
the RF measured in most labs is ____
IgM
RF is most commonly associated with _____ (but is not specific for this disease)
rheumatoid arthritis
RF is also present in healthy individuals
T/F
true
Older or younger people have more RF?
RF increases as we age
RF can also be present in nonrheumatic diseases. Name 3
bacterial endocarditis hepatitis parasites viral infection cirrhosis malignancy
a heterogeneous group of autoantibodies directed against nucleic acids and nucleoproteins, e.g. DNA, histones
Antinuclear antibodies (ANA)
When is ANA test indicated?
When patient has a clinical syndrome suggesting systemic lupus erythematosus (SLE) or other connective tissue disease
negative ANA test excludes ____
systemic lupus erythematosus (SLE)
What are two different tests that measure acute phase reactants?
ESR
C-reactive protein
To perform this test, place anticoagulated blood in a vertical tube and measure the rate of fall of erythrocytes in mm/hr
ESR, erythrocyte sedimentation rate
In response to a stimulus such as injury or infection, this can increase up to 1000 times its baseline concentration
C-reactive protein
factors unrelated to inflammation that may result in an increased ESR
obesity
increasing age
drugs
two rheumatic diseases that are almost always associated with an elevated Westergren ESR
polymyalgia rheumatica
giant cell arteritis (temporal arteritis)
use of ESR in rheumatic disease?
assess therapy/treatment effectiveness
this antigen is present in 95% of people with ankylosing spondylitis
HLA-B27
HLA-B27 may be ordered to confirm a diagnosis of ____, ____, or ____
ankylosing spondylitis
Reiter syndrome
anterior uveitis
an ultrafiltrate of plasma to which synovial cells add hyaluronate
synovial joint fluid
normal synovial fluid does not clot because:
because fibrinogen and clotting factors don’t enter the joint space from the vascular space
Arthrocentesis is indicated for diagnosis when one of the following three conditions is suspected:
- septic arthritis
- hemarthrosis
- crystal-induced arthritis
synovial fluid is analyzed for the following 8 characteristics:
viscosity color clarity WBC count PMN culture glucose protein
synovial fluid is reported from the lab as one of these 4 things
normal
non-inflammatory
inflammatory
septic
opaque synovial fluid =
septic
inflammatory synovial fluid = (color)
yellow
inflammatory synovial fluid = (this viscosity)
low (normal is high)
normal synovial fluid = (glucose level as compared to blood)
about the same as blood
inflammatory or septic synovial fluid = (glucose level as compared to blood)
LOWER!!
inflammatory glucose level is lower than blood, septic is MUCH lower than blood
protein level of inflammatory or septic synovial fluid is (lower, higher) than that of normal synovial fluid
HIGHER protein in synovial fluid if inflammatory or septic
WBC count for normal, inflammatory, and septic synovial fluid
normal: < 200
inflammatory: 3,000 - 50,000
septic: > 50,000
(above is from lab book)
PMNs for normal, inflammatory, and septic synovial fluid
normal: < 25%
inflammatory: > 50%
septic: > 75%
ANCA testing is for what diseases?
vasculitic disease!
e.g. Wegener granulomatosis
Normal synovial fluid will have firm, stable clot (hyaluronic, not blood) formation within minutes. What are the mucin clot test results for inflammatory and septic fluid?
inflammatory: variable
septic: friable
contraindications for arthrocentesis:
main contraindication for arthrocentesis: overlying skin lesion or infection
others: coagulopathy, joint prosthesis
