Rheumatoid Diagnostics Flashcards
Basic blood tests
FBC
Urea and electrolytes (U&E)
Liver function tests (LFT)
Bone profile
Erythrocyte sedimentation rate (ESR)
C-reactive protein (CRP)
Liver function tests content
Bilirubin
Alanine aminotransferase (ALT)
Alkaline phosphatase (ALP)
Albumin
Bone profile content
Calcium
Phosphate (PO4)
Alkaline phosphatase (ALP)
CRP
More specific for inflammation
SLE:
-normal
Exception - if significant synovitis or inflammatory pleural or pericardial effusion
Autoantibodies in RA
Rheumatoid factor
Cyclic citrullinated peptides (CCP) antibodies
-more specific than RF
-associated with worse prognosis
Synovial fluid analysis
Suspected septic arthritis
Diagnosing crystal arthritis
Gout - needle shaped and negative
Pseudogout - rhomboid shaped and positive
Septic v Reactive
Synovial fluid culture - positive / sterile
Antibiotic therapy - yes / no
Joint lavage - yes / no
Imaging
X ray
- first line, cheap, widely available
CT scan
-more detailed
MRI
-best for tendons and ligaments
-best for spinal imaging
-expensive and time consuming
Ultrasound
-tendons and ligaments
-good for smaller joints, not for larger
Osteoarthritis X ray features
Joint space narrowing
Subchondral bony sclerosis
Osteophytes
Subchondral cyst
SLE
Autoimmune connective tissue disease
Arthritis
Skin rash
Mouth ulcer
Kidney disease
Pleural effusion
Pericardial effusion
Sjögren’s syndrome
Autoimmune connective tissue disease
Dry eyes
Dry mouth
Extra-articular feature
Polymyositis
Autoimmune connective tissue disease
Muscle inflammation
Weakness
High CK
FBC
Haemoglobin
-inflammatory arthritis: decrease or normal
-osteoarthritis: normal
-septic arthritis: normal
MCV
-normal
-normal
-normal
WCC
-normal
-normal
-increase (leukocytosis)
Platelet count
-normal or increase
-normal
-normal or increase
U&E content
Urea
Creatinine
Sodium
Potassium
U&E
High creatinine is worse renal clearance
Rheum disease can affect kidneys
-SLE - lupus nephritis
-vasculitus - nephritis
-NSAIDs can cause kidney impairment
Liver function test
DMARDs can cause liver damage
Patients in methotrexate need regular blood tests
Low albumin - either problem of synthesis or problem of leak from kidney
Bone profile
Paget’s disease of bone: increased ALP
Osteomalacia: ALP normal or increased, Ca and PO4 normal or decreased
Osteoporosis: all normal
ESR
Elevated due to
-elevated immunoglobulin level
-paraprotein (myeloma)
-anemia
-tends to rise with age
SLE:
-high
Anti nuclear antibodies (ANA)
High titre ANA in combination with correct clinical features may indicate one of the autoimmune connective tissue diseases
Only order if suspected autoimmune connective tissue disease
Neg rules out SLE
Pos not necessarily SLE
If ANA is positive
Extractable nuclear antigens (ENA)
Ro- lupus or sjogrens
La - lupus or sjogrens
RNP - lupus or mixed connective tissue disease
Smith - lupus
Jo-1 - polymyositis
Rheumatoid arthritis X ray
Soft tissue swelling
Peri-articular osteopenia
Bony erosions
Rheumatoid arthritis ultrasound
Synovial hypertrophy
Increased blood flow
May detect erosion not seen on X ray
Better for synovitis
Scleroderma
Autoimmune connective tissue disease
Vasculopathy
Skin thickening
Organ fibrosis
