Clinical Serology, Lab Testing, & Gout/Pseudogout Flashcards
Acute phase reactant that is a marker of inflammation
Rises with age, higher in women, and monitors disease activity
ESR
ESR is utilized to monitor disease activity, especially _____ and ______
Polymyalgia rheumatica; giant cell arteritis
CRP is an acute phase reactant that is a marker of inflammation and is utilized as an assessment of disease activity.
It is synthesized in the ______. Proinflammatory ______ increase the CRP.
CRP can also activate ______ and promote phagocytosis
A CRP reading of >8 mg/L is inflammatory
Liver; cytokines
Complement
T/F: ESR rises and falls more quickly than CRP
False; CRP rises and falls quicker than ESR
Examples of general inflammatory markers other than ESR and CRP
Leukocytosis Thrombocytosis Ferritin Fibrinogen Complement (decreases)
IgM autoantibody that targets the Fc portion of IgG immunoglobulin
Rheumatoid factor
RF is produced by _____ cells in ______ joints of RA pts
B cells; synovial
RF is present in 70% of pts with RA, and is present in 100% of pts with _______ RA
Nodular
Besides RA, what conditions might reveal a positive RF?
Sjogrens syndrome Cryoglobulinemia Primary biliary cirrhosis Mixed CT disease Endocarditis; chronic infections SLE Sarcoidosis Malignancy Lung disease
The cutoff value for positive RF depends on lab method; positive RF > 45 IU/mL by ELISA or >1:80 by latex fixation.
Higher RF levels are correlated with what features of the inflammatory disease process?
High levels associated with more aggressive disease, joint erosions, and worse px
_______ antibodies are present in 70% of pts with early RA and have more specificity characteristics of RA than RF
Anti-cyclic citrullinated peptide (anti-CCP)
______ antibodies + _____ = 99.5% specificity for RA
Anti-CCP; RF
Antibody directed against nuclear antigens; may be found in normal pts as well as those with RA, CTD, malignancy, etc. (nonspecific!!); pattern of immunofluorescence gives clues to dx
Anti-nuclear antibody (ANA)
Homogenous ANA pattern
Histone antibody — 95% of drug-induced lupus
Rim pattern of ANA
Anti-dsDNA — 50% SLE
Speckled ANA pattern
Anti-Sm (smith) — lupus
Anti-SS-A/SS-B — Sjogren
________ and _____ antibodyies are associated with scleroderma CREST/progressive systemic sclerosis
Anticentromere; anti-scl 70
Hematologic criteria/findings in SLE
Hemolytic anemia with reticulocytosis
[or]
Leukopenia (<4000/mm3 total)
[or]
Lymphopenia (<1500/mm3) on 2 or more occasions
[or]
Thrombocytopenia (<100,000/mm3)
Immunologic findings associated with lupus
Anti-DNA Abs
Anti-Sm
Antiphospholipid antibodies (IgG or IgM cardiolipin Abs)
Positive lupus anticoagulant
False positive RPR (syphilis test)
ANA
What is the significance of a positive antistreptolysin O antibody (ASO) and/or anti-DNAase B titer?
Evidence of a preceding group A streptococcal infection
[Clinically may see acute rheumatic fever, polyarticular asymmetric arthritis of large joints, may cause post-streptococcal reactive arthritis (symmetric and affects small joints)]
A 46 y/o male presents with fatigue, malaise, pain in both wrists, and bilateral swelling over MCP joints. He admits to previous hx of lupus. The symptoms have been present for 6 weeks. PE reveals decreased strength in both hands, swollen wrists, PIPs, and MCP joints bilaterally, and a nodule on the extensor surface of the left arm. Which lab test would you expect to be abnormal in this case?
A. CBC indicating hemolytic anemia, leukocytosis, and negative RPR
B. Low complement C3, decreased ferritin, and elevated platelet count
C. Positive anti-CCP, elevated ESR, and elevated RF level
D. Positive ANA, negative RF, and elevated CRP
E. Thrombocytosis, hypocalcemia, and normal ESR
C. Positive anti-CCP, elevated ESR, and elevated RF level
Hyperuricemia is defined as a uric acid > _______ mg/dL that may be due to overproduction or underexcretion of uric acid. It is associated with development of gouty arthritis which consists of ___________ crystals in joint fluid or tophi.
Crystals are needle-shaped, ______ birefringent by polarized light microscopy.
Attacks are acute in onset, monoarticular, often the 1st MTP joint (_______). Often nocturnal awakening.
6.8; monosodium urate
Negative
Podagra
Nodular deposits of monosodium urate crystals in skin
Tophi
90% of gout cases are in men (4th-6th decade) or ________ women
Post-menopausal
________ and ______ are dietary risk factors that promote increased urate production and decreased excretion
Alcohol; red meat
Acute vs. chronic gout tx
Acute:
NSAIDs
Colchicine (GI toxicity)
Steroids
Chronic:
Xanthine oxidase inhibitor
Uricosurics
Probenecid — blocks tubular resorption of urate and increases uric acid excretion
Imaging study that may not detect early erosive arthritic disease but may show symmetrical involvement of MCPs in RA, periarticular osteopenia (decreased bone mass, bone loss), and erosions
Plain radiography
[digital radiographs have high spatial resolution but have poor visualization of soft tissue]
Imaging study that is sensitive for soft tissue abnormalities like synovitis, tendonitis, bursitis, as well as evidence of joint erosions
May aid in injecting/aspirating joint, and do not involve radiation
Ultrasound
Imaging study useful for soft tissue abnormalities; utilizes gadolinium contrast which is taken up in inflamed synovium (thickened pannus) but contrast may cause nephrogenic systemic fibrosis in pts with renal disease
Good modality for spine, SI, synovitis, tenosynovitis, erosions, and joint inflammation
MRI
Best imaging study for bony abnormalities (trabecular, cortical bone), erosions, fractures, degenerative or inflammatory arthritis
CT
Which is more sensitive for bone erosions — MRI or CT?
CT
A 50 y/o carpenter presents with pain, swelling, and decreased ROM in the right elbow. The elbow is swollen and very tender to touch. He relates to doing a lot of hammering, lifting boards, and sawing. Which imaging study is indicated in evaluation of the pts complaint?
A. CT of right arm — att.elbow B. Plain X-rays of elbow C. MRI right arm — att.elbow D. US — att.elbow E. Bone scan — att.elbow
D. US — att.elbow
Criteria for categorizing arthritis
Duration # of joints Symmetry Distribution Inflammation Type of swelling Systemic signs Extra-articular dz Age of pt Nocturnal pain Enthesopathy Response to prior treatment Labs and other tests
GI diseases/syndromes associated with arthritis
UC
Crohns
Behcets
Reactive arthritis with bowel infection
Arthritis manifestations associated with diabetes
Charcot’s joint = gross deformity often affecting ankle or foot in diabetic pt with clinical features including loss of sensation, loss of proprioception, and increased susceptibility to infection
Cheiroarthropathy — arthritic pain, tightness/thickening of skin due to extra collagen buildup
Joint manifestations of thyroid disease
Carpal/tarsal tunnel syndrome
Cytoid bodies and vasculitis are associated with what ophthalmologic manifestation?
Retinopathy
2 main complications of chronic gouty arthritis
Tophi (ears, forearms, achilles tendon)
Renal insufficiency (radiolucent urate stones)
Asymptomatic hyperuricemia should not be treated. What is the one exception?
Pt about to receive cytotoxic therapy for a neoplasm
2 xanthine oxidase inhibitors
Allopurinol
Febuxostat
2 drugs that inhibit inflammation caused by crystal precipitation and joint inflammation in acute gout
NSAIDs (naproxen, indomethacin)
Colchicine
Urinary excretion of uric acid can be promoted by what drug?
Probenecid
Oral, parenteral, or intra-articular _____ can be a reasonable first line tx in acute gout; caution in HF, HTN, poorly controlled DM, sepsis, and CKD pts
Steroids (prednisone)
Gout tx effective within 1st 24 hrs of atack; side effects are usually GI — N/V/D
Colchicine
IL-1B antagonist (biologic) that may be administered subcutaneously to tx gout
Anakinra
Indications for uric acid lowering agents
Recurrent gouty attacks, tophi, renal stones, cytotoxic chemotherapy
[DO NOT start during acute attack — can precipitate flare; DO NOT use with CKD or stones]
Pseudogout (Calcium pyrophosphate dehydrate deposition disease) typically affects larger joints, particularly the _____, in older pts. It can be polyarticular and presents similarly to gout. If chronic, it can resemble ______.
A complication is _____ which is calcium deposits in articular cartilage. Treatment is similar to true gout
Knee; OA
Chondrocalcinosis
Short blunt rods, rhomboids/cuboids and weak positive birefringence by polarizing microscopy
Pseudogout
Pseudogout (CPPD) is associated with aging. If it is found in younger pts, what are some diseases to consider?
Primary hyperparathyroidism
Hemochromatosis
Hypomagnesemia
Chronic gout
Gitelman’s syndrome
