Rheumatology Diagnostics Flashcards
What are the diagnostic tests available for rheumatology?
- blood tests
- joint (synovial) fluid analysis
- imaging tests
What imaging is available for rheumatology?
- x-rays
- US
- CT
- MRI
What blood tests are done for rheumatology?
- FBC
- U+Es
- LFTs
- Bone profile
- ESR
- CRP
What are the main types of arthritis?
- osteoarthritis
- inflammatory arthritis
- septic arthritis
What would you see on an FBC with inflammatory arthritis?
Hb = anaemia or normal MCV = normal WCC = normal Platelet = normal/raised
What would you see on an FBC with osteoarthritis?
Hb = normal MCV = normal WCC = normal Platelet = normal
What would you see on an FBC with septic arthritis?
Hb = normal MCV = normal WCC = increased/leucocytosis Platelet = normal/increased
What does a higher creatinine?
worse renal clearance (indicating kidneys problem)
What is the effect of systemic lupus erythematous on the kidneys?
lupus nephritiis
What is the effect of vasculitis on the kidneys?
nephritis
What is the effect of chronic inflammation on the kidneys?
- high levels of serum amyloid A (SAA) protein
- SAA deposits in organs (AA amyloidosis)
What does a low albumin reflect?
- problem of synthesis (in liver)
- problem of leak from kidney (eg in lupus nephritis)
What is the effect of Disease Modifying anti-rheumatic drugs on the liver?
can cause liver damage
- pts on methotrexate need regular blood tests (every 8 weeks)
What is tested in a bone profile?
- Calcium
- Phosphate
- Alkaline phosphatase
What is Paget’s disease?
an abnormality of high bone turnover
What are the clinical features of Paget’s disease?
- bone pain
- excessive pain growth
- fracture in areas of abnormal bone
What can be seen in a bone profile if the patient has Paget’s disease?
raised ALP
What is osteomalacia?
soft bones due to vitamin D deficiency
How does osteomalacia present on a bone profile?
ALP: normal or raised
Ca and PO4: normal or low
What is osteoporosis?
low bone density
How does osteoporosis present on a bone profile?
Calcium, phosphate and ALP normal
What can cause a raised ESR?
- inflammation
- elevated immunoglobulin level
- paraprotein (myeloma)
- anaemia
- increasing age
How does SLE present on an inflammation profile?
ESR: high
CRP: normal
When can CRP be high in SLE?
- significant synovitis
- inflammatory pleural/pericardial effusion
What should be done if there is an elevated CRP in lupus?
have a low index of suspicion for infection
What are the 2 types of antibodies found in the bloods of RA patients?
- rheumatoid factor
- cyclic citrullinated peptides
What is rheumatoid factor?
Antibodies that recognize the Fc portion of IgG as their target antigen typically IgM antibodies i.e. IgM anti-IgG antibody
How common is rheumatoid factor?
- positive in 70% at disease onset
- further 10-15% become positive over the first 2 years of diagnosis
What are cyclic citrullinated peptides?
- more specific than RF
- associated with a worse prognosis
What are anti-nuclear antibodies?
antibodies directed at the nuclear component of the cell
What is known about non-specific anti-nuclear antibodies?
- Relatively common in general healthy population at low titre (level)
- Prevalence of ANA increases with age
- Sometimes transiently positive following infection
What is the use of anti-nuclear antibodies in rheumatology?
high titre ANA with correct clinical features can indicate an autoimmune connective tissue disease
What can a high ANA level with clinical features suggest?
- SLE
- scleroderma
- Sjogern’s syndrome
What are the clinical features of SLE?
- Arthritis
- Skin rash
- Mouth ulcers
- Kidney disease
- Haematological
- Pleural effusion
- Pericardial effusion
What are the clinical features of Scleroderma?
- Vasculopathy (esp. Raynaud’s phenomenon)
- Skin thickening
- Organ fibrosis
What are the clinical features of Polymyositis?
- Muscle inflammation
- Weakness
- High CK
What are the clinical features of Sjorgen’s syndrome?
- Dry eyes
- Dry mouth
- Extra-articular features
How is ANA reported?
as a maximal dilution at which it is still detectable
What does a negative ANA test exclude?
SLE
What does a positive ANA test suggest?
suggestive of SLE if clinical and lab features support
What other tests should be ordered if ANA is positive?
- ENA (extractable nuclear antigens)
- double stranded (dsDNA) antibodies
- complement levels C3 and C4
What is tested for in an ENA panel?
- Ro
- La
- RNP
- Smith
- Jo-1
What does a positive Ro antibody test suggest?
Lupus or Sjogrens syndrome
What does a positive La antibody test suggest?
Lupus or Sjogrens syndrome
What does a positive RNP antibody test suggest?
Lupus or mixed connective tissue disease
What does a positive Smith antibody test suggest?
Lupus
What does a positive Jo-1 antibody test suggest?
Polymyositis
What does a positive dsDNA antibody test suggest?
- highly specific for lupus
- associated with renal involvement
- useful for tracking lupus activity over time
What does reduced complement levels of C3 and C4 suggest?
active lupus
How do you do a synovial fluid analysis?
obtained by aspirating fluid from a joint
What are the indications for joint aspiration?
- Diagnostic: to obtain synovial fluid for analysis
- Therapeutic: to relieve symptoms (+/- concurrent steroid injection)
What are the 2 main diagnostic uses of aspiration?
- suspected arthritis
(send for MC+S, identification of causing organism, sensitivities for ABx) - diagnosing crystal arthritis
What is the gold standard tests to diagnose suspected septic arthritis?
aspiration for a synovial fluid analysis
How does a diagnosis of crystal arthritis occur?
- aspirating fluid from the affected joint
- examination under a microscope using a polarised light
How does gout present in a synovial fluid arthritis?
needle shaped crystals with negative birefringence
How does pseudogout present in a synovial fluid arthritis?
rhomboid shaped crystals with positive birefringence
How does a synovial fluid culture present in septic arthritis?
positive
How does a synovial fluid culture present in reactive arthritis?
sterile
Is ABx therapy recommended in septic arthritis?
yes
Is ABx therapy recommended in reactive arthritis?
no
Is joint lavage recommended in septic arthritis?
yes - in large joints
Is joint lavage recommended in reactive arthritis?
no
What is the first line imaging in rheumatology?
x-rays
Why are MRIs used in rheumatology?
- Best visualization of soft tissue structures like tendons and ligaments
- Best for spinal imaging: can see spinal cord and exiting nerve roots
- but, Expensive and time-consuming
Why are US used in rheumatology?
- can visualize soft tissue structures.
- Good for smaller joints, less good for deep/large joints like knee or hip
What are the XR features of osteoarthritis?
- joint space narrowing
- subchondral bony sclerosis
- osteophytes
- subchondral cysts
What causes the joint space narrowing on a XR of osteoarthritis?
loss of articular cartilage leading to bone to bone contact
What are osteophytes?
bone spurs
What features of rheumatoid arthritis can be seen on a XR?
- soft tissue swelling
- peri-articular osteopenia
- bony erosions
- joint space narrowing
When do bony erosions occur?
- only in established disease
- aim is to treat before formation
Why can US be better than XR in rheumatoid arthritis?
better to detect synovitis
What features of rheumatoid arthritis can be seen on a US?
- Synovial hypertrophy (thickening)
- Increased blood flow (seen as doppler signal)
- May detect erosions not seen on plain X-ray
When does joint space narrowing occur in oestoarthritis?
primary abnormality
When does joint space narrowing occur in rheumatoid arthritis?
secondary damage due to synovitis
What are Heberden’s nodes?
osteophytes at the distal inter-phalangeal joints
What are Bouchard’s nodes?
osteophytes at the proximal inter-phalangeal joints
What is a common early radioactive sign of inflammatory arthritis?
juxta-articular osteopenia
Where do bony erosions tend to occur?
the margins of the joint where the synovium is in direct contact with bone
What are the radiographic features of gout?
juxta-articular ‘rat bite’ erosions at the metaphalangeal joint of the big toe
What are the radiographic features of psoriatic arthritis?
- asymmetrical pattern of joint involvement
- erosions of interphalangeal joints
- MCPJs not affected
What investigations should be done for suspected SLE?
- ESR, CRP
- haematology
- renal function tests
- antibodies and complement
- clotting
What would be seen on a haematology screen for SLE?
- haemolytic anaemia
- lymphopenia
- thrombocytopenia
What renal function tests should be done in SLE?
- uP:CR
- albumin
What would be included immunological screen for SLE?
- anti-nuclear antibodies
- anti-double-stranded DNA antibodies
- complement consumption
What would be seen on a clotting screen for SLE?
- anti-phospholipid antibodies
- lupus anticoagulant
- anti-cardiolipin antibodies
What would be seen immunological screen for SLE?
- low complement C3 and C4
- high levels of anti-ds-DNA antibodies
What are the aims when treating SLE?
remission or low disease activity and flare prevention
What medication is recommended in all patients with lupus?
hydroxychloroquine
What treatment should be minimised/withdrawn for SLE?
maintenance treatment glucocorticoids
What can help reduce the usage of maintenance treatment glucocorticoids?
the appropriate initiation of immunomodulatory agents (methotrexate, azathioprine, mycophenolate)
What treatment is used in persistently active or severe SLE?
- cyclophosphamide
- B cell targeted therapies (rituximab and belimumab)
What should patients with SLE be assessed for?
- anti-phospholipid antibody status
- infectious and CVD risk profile
What is Sjögren’s syndrome?
autoimmune exocrinopathy:
- lymphocytic infiltration of exocrine glands and occasionally other organs (extra-glandular involvement)
How does Sjögren’s syndrome present?
- xerophthalmia (dry eyes)
- xerostomia (dry mouth)
- parotid gland enlargement
What are the most common extra-glandular manifestations in Sjögren’s syndrome?
- non-erosive arthritis
- Raynaud’s phenomena
What is meant by secondary Sjögren’s syndrome?
if it occurs in the context of another connective tissue disorder
What tests can be done if Sjögren’s syndrome is suspected?
- salivary gland biopsy
- Schimer’s test
What will a salivary gland biopsy show in Sjögren’s syndrome?
- lymphocytic infiltration
- predominantly CD4 helper T cells
- less so: B lymphocytes
What will a salivary Schimer’s test show in Sjögren’s syndrome?
<5mm after 5 minutes
What is Schimer’s test?
test to assess tear production
- filter paper under the lower eyelid
- extent of wetness measured after 5 minutes
- abnormal is <5mm after 5 minutes
What is inflammatory muscle disease?
Proximal muscle weakness due to autoimmune-mediated inflammation either with (dermatomyositis) or without (polymyositis) a rash
What are the skin changes seen in dermatomyositis?
- lilac-coloured (heliotrope) rash on eyelids, malar region and naso-labial folds
- red/purple flat/raised lesions on knuckles (Gottron’s papules)
- subcutaneous calcinosis
- fissuring and cracking of the skin (mechanic’s hands)
What is associated with inflammatory muscle disease?
- malignancy (10-15%)
- pulmonary fibrosis
What is systemic sclerosis?
- thickened skin with raynaud’s phenomenon
- dermal fibrosis
- cutaneous calcinosis
- telangiectasia
What are the 2 different types of systemic sclerosis?
- limited
- diffuse
What is seen in limited systemic sclerosis?
- fibrotic skin, hands, forearms and face
- anticentromere antibodies
- pulmonary hypertension
- Hx of raynaud’s phenomenon - CREST
What dose CREST stand for?
- Calcinosis
- Raynaud’s phenomenon
- Esophageal dysmotility
- `Sclerodactylly
- Telangiectasia
What is seen in diffuse systemic sclerosis?
- Fibrotic skin proximal to elbows or knees (excluding face and neck)
- Anti-topoisomerase-1 (anti-Scl-70) antibodies
- Pulmonary fibrosis, renal (thrombotic microangiopathy) involvement
- Short history of Raynaud’s phenomenon
What is overlap syndrome?
When features of more than 1 connective tissue disorder are present e.g. SLE and inflammatory muscle disease we can use the term overlap syndrome
What tests are done and seen in suspected inflammatory muscle disaster/
- high CPK
- abnormal electromyography
- abnormal muscle biopsy
What would be seen in abnormal muscle biopsy?
polymyositis:
- CD8 T cells
dermatomyositis:
- CD4 T cells in addition to B cells
When is the term undifferentiated connective tissue disorder?
When incomplete features of a connective tissue disease are present
What antibody can be used to identify different connective tissue disorders?
Anti-U1-RNP antibody
What are the key auto-antibodies in diffuse systemic sclerosis?
Anti-Scl-70 antibody
also termed antibodies to topoisomerase-1
What are the key auto-antibodies in limited systemic sclerosis?
Anti-tRNA transferase antibodies
E.g. histidyl transferase (also termed anti-Jo-1 antibodies)
What are the key auto-antibodies in dermato/polymyositis
Anti-tRNA transferase antibodies
E.g. histidyl transferase (also termed anti-Jo-1 antibodies)
What are the key auto-antibodies in Sjören’s syndrome?
-No unique antibodies but typically see:
- Antinuclear antibodies
- Anti-Ro and anti-La antibodies
Rheumatoid factor
What are the key auto-antibodies in mixed connective tissue syndrome?
Anti-U1-RNP antibodies
