Interpretation of Rheum Tests Flashcards
proportion of patients with positive test who have the disease…. So a negative test will effectively “rule out” disease
sensitivity (SNOUT)
proportion of patients with negative test who do not have the disease….. So a positive test will effectively “rule in” a disease.
specificity (SPIN)
indirect measurement of serum APR concentrations, particularly fibrinogen. Influenced by the size, shape, and number of RBC’s. Changes relatively slowly
ESR
What happens to the ESR with anemia and polycythemia vera?
increased in anemia and decreased in polycythemia
Elevated in obesity due to IL-6 secretion by adipose tissue
ESR and CRP
“Normal” ESR values
Male <10mm/hr
For what two rheumatic conditions is an elevated ESR most helpful?
Polymyalgia Rheumatica and Giant Cell Arteritis
Produced in response to inflammation. Enhances complement binding and phagocytosis. Acute increase within 6 hours; peaks at 48 hours
CRP
Normal CRP values for adults
adults: normal is less than 1mg/L and abnormal is greater than 10.
An AUTO ANTIBODY directed against Fc portion of IgG
Rheumatoid factor
Percent of patients with RA who are RF negative early in the disease
30%
Normal RF value
<1:80 considered negative
correlates with severe articular disease and extra-articular manifestations
RF (rheumatoid factor)
Antibody directed against “citrullinated” peptide residues present within inflammatory sites. Mostly associated with RA
Anti-CCP (citrulline antibody, CCP antibodies)
Greater specificity than RF, useful when RF is negative
Anti-CCP (citrulline antibody, CCP antibodies)
Autoantibodies directed at nuclear antigens (or contents of cell nucleus). Hallmarks of systemic autoimmune disease
Anti-nuclear Antibodies (ANA)
Provide further diagnostic and prognostic data concerning pts who have minimal sx’s or who have clinical features of more than 1 autoimmune disease
Anti-nuclear Antibodies (ANA)
How many criteria for lupus should be met before ordering an ANA?
3 of the 11
Specific for SLE (60-70%). Single stranded DNA nonspecific. May fluctuate with disease activity
Anti-dsDNA
Highly specific for SLE (but not sensitive)
Anti-Sm (smith antigen)
Associated with CREST, and scleroderma
Anti-centromere antibody (ACA)
Associated with diffuse scleroderma
Anti-topoisomerase I (Scl-70)
Associated with Sjogren’s. Can be seen in SLE. May be associated with neonatal heart block in babies of mothers with this antibody
Anti-Ro (SS-A) and La (SS-B)
Part of criteria for mixed connective tissue disease.
Anti-U1 snRNP
Specific for myositis associated with interstitial lung disease and Raynaud’s
Anti-Jo-1 (anti-histidyl-tRNA synthestase)
useful for monitoring disease activity in SLE. Low levels indicate activation of complement cascade and consumption of complement
serum complements
Group of autoantibodies mainly of the IgG type directed against antigens in the cytoplasm of neutrophil granulocytes and monocytes
Antineutrophil Cytoplasmic Antibodies (ANCA)
most strongly associated with vasculitis
ANCA
Syndrome associated most with HLA-B27
ankylosing spondylitis
Normal Uric acid levels for adults
men: 4-8.5 mg/dL. women: 2.7-7.3 mg/dL
What type of antineutrophil cytoplasmic antibody is associated with Churg-Strauss vasculitis
p-ANCA
What syndrome is associated with a positive ANA and anti-centromere AB?
CREST
What autoimmune disease is associated with eosinophilia, a positive ANA (either anti-Scl or nucleolar), and sometimes a positive RF?
systemic sclerosis (scleroderma)
What syndrome is associated with positive anti-Ro (SS-A) or anti-La (SS-B) antibodies?
Sjogren’s
What syndrome is associated with a low titer of ANA, but presence of nuclear RNP antibodies?
mixed connective tissue disorder
What disorder is associated with positive ANA, anti-PM-Scl and increased CPK/aldolas enzymes?
dermatomyositis
