7. Clinical Serology and Lab Testing Flashcards
Acute phase reactants- immediate response to inflammatory stimuli and are NONspecific indicators including ESR which rises with age and is higher in women but can be used to monitor disease activity. What is the other acute phase reactant that is nonspecific and can be used for assesment of disease activity, is synthesized in the liver, increased by proinflam cytokines (IL6?) and can acitvate complement and promote phagocytosis?
C-Reactive Protein CRP
A CRP greater than 8 is inflammatory, it rises and falls quicker than ESR, associated with leukocytosis, thrombocytosis, ferritin, fibrinogen and complement increase with inflammation, complement decreases when immune complexes do what?
mediate its consumption
What is an IgM* autoantibody that targets the Fc portion of IgG immunoglobulin, can be any subclass but M is MC, it is produced by B cells in the synovial joints of RA patients, sensitivity for RA is 66% and specificity is 82%, 70% of RA patients have this, and 100% with nodular RA have this**?
Rheumatoid factor
Rheumatoid factor is also found in healthy patients, and in 20% of ppl >60, and is positive in many other conditions including sjogrens/cryoglobulinemia, primary biliary cirrhosis, mixed connective tissue, SLE, and others, 30% of RA pts are RF negative, and what are high levels of RF associated with?
Aggressive disease, joint erosions and worse prognosis
What antibodies are present in 70% of patients with RA, and have more specificity characteristics of RA than RF (96%, 78% sensitivity), if this ab AND RF is positive the specificity for RA is 99.5%***** associated w more aggressive and erosive disease?
Antibodies to citrullinated proteins
Anti-cyclic citrullinated peptide
Anti-CCP
anit nuclear antibody or ANA is directed against nuclear antigens occur in normal patients 30% of time and RA, CTD, and malignancy + different patterns of IF of ANA:
Homogenous= histone antibody seen in drug induced lupus
rim pattern= anti DS DNA = SLE
Speckled = Anti SM (SMITH) = lupus/antiSS-A/B=sjogrens
Anticentromere ab = scleroderma
Anti scl 70=?
scleroderma / crest/ pss
What are the following characteristic of? malar rash discoid rash photosensitivity oral uclers arthritis serositis renal- proteinuria + casts seizures and psychosis Blood: Hemolytic anemia with reticulocytosis, leukopenia, lymphopenia, thrombocytopenia
SLE
- **Positive lupus anticoagulant = elevated PTT
- **False Positive RPR (syphilis)
What antibody is evidence of preceding group A strep infection, elevated or rising titer, causing acute rheumatic fever resulting from immune reaction to infection, may cause arthritis, polyarticular and migratory with fever, usually affecting large joints and is asymetric*?
Antistreptolysin O Antibody (ASO titer) and anti DNAase B titiers (less common)
Aspiration of RA joint would show normal fluid that is clear and viscous with little cell count, non-inflammatory w 200-2000 mononuclear cells, if inflam was present PMNs 2000-5000 and how high would it be if the patient was septic and the fluid was cloudy and opaque?
> 50000 = septic
What causes gouty arthritis, and is monosodium urate crystals in joint fluid and or tophi, crystals are needle shaped and negative birefringent by polarized light, due to over production or underexcretion, acute onset- mono*articular often great toe?
Uric acid - hyperuricemia (>6.8)
Uric acid - hyperuricemia can attack knees, feet ankles, joints are hot swollen tender dusky red with fever, tophi may be present which are nodular deposits of monosodium urate crystals in skin, 90% of gout in men and post menopausal women, alcohol prommotes increased urate production and decreased?
Excretion
What imaging study is digital radiographs have high spatial resolution, poor visualization of soft tissue*, RA symmetrical involvement of MCP periarticular osteopenia, erosions, plain films may not detect early erosive arthritic dz?
Radiography
What imaging study is sensitive for soft tissue abnormalities (synovitis, tendonitis, bursitis) and erosions, aids in injection and aspirating joint and has no radiation?
Ultrasonography
What imaging study is is useful for soft tissue abnls, gadolinium contrast taken up in inflamed synovium (thickened pannus) IV gadolinium can cause nephrogenic systemic fibrosis in patient with kidney disease, good for spine, SI synovitis, tenosynovitis, erosions, and joint inflam?
MRI
What imaging study is best for bony abnormalities (trabecular/cortical bone) erosions, fractures, degerative or inflammatory arthritis, more sensitive than MRI for bone erosions?
CT
