1 Rheum Labs Flashcards
How might a patient with SLE present?
Woman with Fatigue x 6 months
Intermittent pain and swelling BL hand/fingers and knees x 3-4 months
Occasional sharp chest discomfort with a deep breath
Redness on cheeks
Fingers change colors and become painful when she goes to frozen section of store
ACR criteria for SLE Dx
(4 or more of the following)
Malar rash
Photosensitivity
Polyarthritis
Renal disorders (proteinuria, cellular casts)
Hematologic disorders (anemia, leukopenia, thrombocytopenia)
(+) Anti-DNA (+) anti-SM, (+) antiphospholipid Ab
Discoid rash
Mucosal ulcers
Serosa this (pleuritic or pericarditis)
Neurological disorders (HA, seizures, etc)
(+) ANA
General lab work results for SLE
CBC: Anemia, Leukopenia, and/or Thrombocytopenia
Serum creatinine: elevated with renal dysfunction
U/A: hematuria, proteinuria, cellular casts
LFTs
ESR/CRP: elevated with inflammation
C3 and C4: Low complement levels indicate active lupus
What is the relationship between ANA and SLE?
(+) in >95%
Cardinal feature BUT NOT SPECIFIC
ANA is reported in what 2 parts?
Titer of antibodies with serial dilution (ie 1:40)
Staining pattern of antibodies (homogenous, speckled, nucleoli, centromere)
• Loosely associated with underlying autoimmune disease - not specific
Following a positive ANA in suspected SLE cases, what should you order?
Anti-dsDNA antibodies
Anti-Sm (anti-Smith) antibodies
Antibody that is useful for distinguishing patients with SLE because it is rarely found in other disorders
Anti-dsDNA
Useful in clinical management too b/c often fluctuates with SLE disease activity
Antibody that is detected in 10-50% of SLE patients and generally remains positive, even in remission
Anti-Sm antibody
What are antiphospholipid antibodies?
Anticardiolipin Ab, Beta 2 glycoprotein Ab, Lupus anticoagulant
Present in patients with antiphospholipid syndrome
What is antiphospholipid syndrome?
Primary condition OR in the setting of an underlying disease, usually SLE
Arterial, venous thromboembolic events and RECURRENT FETAL LOSS
How might a patient with Rheumatoid Arthritis present?
40 yo woman with fatigue x 6 months
Intermittent aching and occasional redness and swelling in hands, fingers, and knees x 3-4 months
MORNING STIFFNESS that lasts about 2 hours. Tylenol no help. Ibuprofen minimal help.
No myalgia/weakness
Mild erythema and soft tissue swelling of the PIP and MCP BUT DIPs SPARED
ULNAR DEVIATION at MCPs
Lab results you might see in a patient with RA
ESR: 62 mm/hr (normal <20)
CRP: 4.0 mg/dL (normal 1.0)
CBC w diff: normal except MILD thrombocytosis
ANA: positive at 1:80 with immunofluorescent-stained speckled pattern
Serum uric acid: 3.4 mg/dL (normal)
RF: can be positive OR negative
Test with moderate specificity for RA
Rheumatoid Factor
Associated with several autoimmune/rheumatologist and non-rheumatic diseases, so need to order with antiCCP
Rheumatic diseases associated with Rheumatoid Factor
RA Sjogren syndrome Mixed connective tissue disease SLE Polymyositis or Dermatomyositis
Non rheumatic diseases associated with RF
Bacterial endocarditis Hep B or C TB Sarcoidosis Malignancy Primary biliary cholangitis
What lab is helpful to support dx of RA and is recommended to be ordered together with RF?
Anti-CCP
Testing for antibodies to citrullinated peptides (ACPA) - antibodies against cyclic citrullinated peptides is the most commonly used assay
Specificity for RA is HIGH
How might Sjogren Syndrome present?
49 YO female with fatigue x 6 months
Dry mouth and dry eyes
Recent cavities
Joints and muscles ache diffusely
What labs should you order for Sjogren?
Anti-Ro/SSA
Anti-La/SSB
ANA
ANA is positive for 95% of Sjogren patients. What can you order with it to be more specific for Sjogren?
Anti-Ro/SSA and Anti-La/SSB
Generally 60-80% of patients with primary Sjogren syndrome exhibit one or both of these antibodies
How does polymyalgia rheumatica typically present?
82 yo female with fatigue
Recent onset of aching pain in upper arms, low back, hips, thighs (makes it hard to brush hair)
Morning stiffness for over an hour and with long car rides
Active shoulder ROM decreased bilaterally
What non-specific inflammatory markers should you order if suspecting polymyalgia rheumatica?
ESR/CRP
Characteristic finding in PMR is elevated ESR and/or CRP
Associated with giant cell temporal arteritis
How would fibromyalgia present?
31 yo female with fatigue x 6 months
“Hurt all over” - myalgia and arthralgia
Sleeps 10 hours but wakes up still exhausted
Mind feels “foggy”
PE normal except for multiple tender points
What would you expect lab report to show in fibromyalgia patients?
NORMAL (CBC, ANA, RF, CRP, ESR)
How would you expect ankylosing spondylitis to present?
32 yo male with fatigue x 6 months
Ongoing low back pain and progressive stiffness
Symptoms worse in morning
LBP improves with exercise but worse with inactivity
Hx of plantar fasciitis
What would imaging reveal in ankylosing spondylitis patients?
Bamboo spine
Sacroiliitis
What lab is characteristically abnormal in ankylosing spondylitis?
Human Leukocyte Antigen (HLA)-B27
Seen in other spondyloarthropathies as well (Reactive arthritis, psoriatic arthritis, arthritis/spondylitis associated with IBD)
How does scleroderma present?
51 yo female with fatigue x 6 months
Thickening and tightening of the skin on hands/face
Food sometimes more difficult to swallow
Pain in fingers when they get cold
Multiple telangiectasias on skin
What are the CREST symptoms for scleroderma?
Calvin Osi’s Reynaud syndrome Esophageal involvement Sclerodactyly Telangiectasias
What test is used to support the diagnosis of CREST syndrome (limited Systemic Sclerosis - scleroderma)?
Anticentromere Antibodies (ACA)
Found in a high percentage of patients with limited SSc/CREST
ANA will also be positive in 95% of patients
Antibodies specific to Systemic Sclerosis
Anti-Scl-70 antibody (Scleroderma antibody)
Aka Antitopoisomerase I antibody
Which test is generally associated with diffuse cutaneous systemic sclerosis and a higher risk of severe interstitial lung disease?
Anti-Scl-70 antibody
“70x worse” than limited Systemic Sclerosis
Absence of antibody does not exclude the diagnosis of scleroderma
What does normal synovial fluid look like?
Viscous fluid, egg white consistency
Role is to reduce friction between articulate cartilage of synovial joints
Aspiration of fluid from synovial joints is called…
Arthrocentesis
Important when evaluating patients with effusion or signs suggesting inflammation within the joint
Arthrocentesis is both…
Therapeutic and Diagnostic
Helpful for diagnosis, relief of pressure, and injection of medications
Most injections consist of a glucocorticoid, local anesthetic, or a combo of the two
Indications for arthrocentesis
New-onset acute mono arthritis
Suspected crystal-induced arthritis (gout, pseudogout)
Suspected infection/septic arthritis
Inflammatory vs noinflammatory arthritides
Unexplained joint, bursa, or tendon sheath swelling
Common sites for arthrocentesis
Shoulder Elbow Hip Knee Wrist Ankle
Most feared complication of arthrocentesis?
Septic joint
Can occur with or w/o glucocorticoid injection
1 in 3000
Risks associated with glucocorticoid injection
Tendon rupture
Nerve damage
Osteonecrosis (ischemic or avascular necrosis of bone)
Minor: skin atrophy, hypopigmentation
Routine analysis of synovial fluid includes:
Gross inspection (clarity, color, viscosity)
Microscopic assessment (gram stain/culture, cell count, crystal detection)
Characteristics of normal synovial fluid
Highly viscous
Clear
Essentially acellular
What are the four categories of joint effusions
Noninflammatory
Inflammatory
Septic
Hemorrhagic
What are examples of noninflammatory joint effusions?
OA
Trauma
Avascular necrosis
What are examples of inflammatory joint effusions?
Septic arthritis RA Spondyloarthritis Lyme Crystal-induced monoarthritis (gout, pseudogout)
What are some examples of septic joint effusions?
Bacterial
Fungal
Mycobacterial
What are some examples of hemorrhagic joint effusions
Hemophilia
Trauma (w/ or w/o fx)
Tumor (malignant or benign)
Anticoagulation
What is the WBC cutoff for inflammatory v noninflammatory?
> 2000 WBC = inflammatory
< 2000 WBC = noninflammatory
What would the WBC count look like with septic joint effusions?
> 20,000
Usually > 100,000**
Is septic arthritis possible if WBC < 100,000?
YES
100,000 WBC/mm3 is septic until proven otherwise
No specific WBC cut-off for septic arthritis but the likelihood of septic arthritis increases as synovial fluid WBC count increases
Using WBC differential to determine if joint effusion is noninflammatory or septic
<25% neutrophils (PMNs) —> noninflammatory
≥75% neutrophils (PMNs) —> septic
Arthrocentesis results:
Turbid, WBC - 88,000 with 90% neutrophils; crystal exam negative; gram stain of fluid shows clusters of gm(+) cocci
Septic arthritis
Septic arthritis is an _______ condition
Urgent
Dx should be made promptly and treatment delivered efficiently to avoid further joint destruction
How might gout present?
Woke up in morning with severe pain in base of L first toe after an evening out (prime rib, cocktails, dancing)
Microscopic assessment of synovial fluid in gout would show…
Monosodium urate crystals
NEGATIVELY birefringent
NEEDLE shaped
How would pseudogout present?
Left knee pain, swelling, redness x 2 days. No fever.
X-ray shows chondrocalcinosis
What would arthrocentesis show in pseudogout?
Calcium pyrophosphate dehydrate (CPPD)
POSITIVELY birefringent
RHOMBOID shape
What is birefringence?
Polarized light microscopy that is the gold standard for evaluating crystals
Determined by using a microscope with polarizing filters and red quartz compensator
Birefringence refers to a particular material’s ability to refract light rays
Negatively birefringent crystals appear ______, while positively birefringent crystals appear _______.
Yellow
Blue
