Rheumatology Diagnositics Flashcards
(76 cards)
1
Q
What are the different types of rheumatology diagnostics?
A
- Blood tests
- Join (synovial) fluid analysis
- Imaging tests, X ray, US, CT, MRI
2
Q
What are the basic rheumatology blood tests?
A
- Full blood count (FBC)
- Urea and electrolytes (U&E)
- Liver function tests (LFT)
- Bone profile
- Erythrocyte sedimentation rate (ESR)
- C-reactive protein (CRP)
3
Q
What is arthritis?
A
disease of joints
4
Q
What are the major divisions of arthritis?
A
- Osteoarthritis (degenerative arthritis)
- Inflammatory arthritis (main type RA)
- Septic arthritis
5
Q
What does the test for Hb show?
A
- Inflammatory arthritis: decreased (anaemia) or normal
- Osteoarthritis: normal
- Septic arthritis: usually normal
6
Q
What does the test for MCV show?
A
- Inflammatory arthritis: normal
- Osteoarthritis: normal
- Septic arthritis: normal
7
Q
What does the test for WCC show?
A
- Inflammatory arthritis: usually normal
- Osteoarthritis: normal
- Septic arthritis: increased (leucocytsosis)
8
Q
What does the test for PLT show?
A
- Inflammatory arthritis: normal or increased
- Osteoarthritis: normal
- Septic arthritis: normal or increased
9
Q
What urea and electrolytes do you measure?
A
Urea (U)
Creatinine (Cr)
Sodium
Potassium
10
Q
What do high creatinine levels indicate?
A
worse renal clearance (indicating kidney problem)
11
Q
How does SLE affect the kidneys?
A
lupus nephritis
12
Q
How does vasculitis affect the kidneys?
A
neohritis
13
Q
How does chronic inflammation affect kidneys?
A
high levels of serum amyloid A (SAA) protein -> SAA deposits in organs (AA amyloidosis)
14
Q
How can NSAIDs affect the kidneys?
A
cause kidney impairment
15
Q
What Liver function tests do you carry out?
A
- Bilirubin
- Alanine aminotransferase (ALT)
- Alkaline phosphatase (ALP)
- . Albumin
16
Q
Why do you do LFTs in rheuamtology?
A
- Disease modifying anti-rheumatic drugs (DMARDs) (eg methotrexate) can cause liver damage.
- patients on methotrexate need regular blood tests (eg every 8 weeks).
17
Q
What does low albumin indicate?
A
reflect problem of synthesis (in liver) or problem of leak from kidney (eg in lupus nephritis)
18
Q
What do you measure in a bone profile?
A
- Calcium
- Phosphate (PO4)
- . Alkaline phosphatase (ALP) nb also in LFTs – confusingly the source of ALP can be bone OR liver
19
Q
What is high in Paget’s disease?
A
ALP
20
Q
What is Paget’s disease?
A
- disease caused by abnormality of high bone turnover
2. Clinical features: bone pain, excessive pain growth, fracture through area of abnormal bone
21
Q
What is osteomalacia?
A
soft bones due to vitamin D deficiency
22
Q
What are the levels like in osteomalacia?
A
- ALP normal or ↑
2. Ca and PO4 normal or ↓
23
Q
What is osteoporosis?
A
low bone density
24
Q
What are the levels like in osteoporosis?
A
usually calcium, PO4 and ALP normal
25
What are two useful markers of inflammation?
ESR and CRP
26
When can ESR be elected but not necessarily form inflammation?
1. Elevated immunoglobulin level
2. Paraprotein (myeloma)
3. Anaemia
4. Tends to rise with age
27
What is more specific for inflammation?
CRP
28
What are the rule of thumb with CRP and ESR in SLE?
1. ESR usually high but CRP normal
2. Exceptions to the rule: CRP high in SLE if there is significant synovitis or there is an inflammatory pleural or pericardial effusion
3. If CRP in lupus, have a low index of suspicion for infection
29
What are the two types of antibodies found in the blood of RA patients?
1. Rheumatoid factor
| 2. Cyclic Citrulinated peptides (CCP) antibodies
30
What is RF?
1. Antibodies that recognize the Fc portion of IgG as their target antigen typically IgM antibodies i.e. IgM anti-IgG antibody !
2. Positive in 70% at disease onset and further 10-15% become positive over the first 2 years of diagnosis
31
What are CCP antibodies?
1. More specific than RF
| 2. Associated with worse prognosis
32
What are anti-nuclear antibodies? (ANA)
antibodies directed at nuclear component of the cell
33
How specific are ANA?
Non-specific
34
Are ANA common?
1. Relatively common in general healthy population at low titre (level)
2. Prevalence of ANA increases with age in the general population
3. Sometimes transiently positive following infection
35
When is ANA used in rheumatology diagnosis?
High titre ANA in combination with the correct clinical features may indicate one of the autoimmune connective tissue diseases (eg SLE, Sjogren’s syndrome, scleroderma)
36
What are some autoimmune connective tissues diseases?
1. SLE
2. Scleroderma
3. Sjogren's syndrome
4. Polymyositis
37
What are the features of SLE?
1. Arthritis
2. Skin rash
3. Mouth ulcers
4. Kidney disease
5. Haematological
6. Pleural effusion
7. Pericardial effusion
38
What are the features of scleroderma?
1. Vasculopathy (esp. Raynaud’s phenomenon)
2. Skin thickening
3. Organ fibrosis
39
What are the features of Sjogren's syndrome?
1. Dry eyes
2. Dry mouth
3. Extra-articular features
40
What are the features of polymyositis?
1. Muscle inflammation
2. Weakness
3. High CK
41
What does a negative tests of Anti-nuclear antibodies (ANA) rule out?
SLE
42
What does a positive test of ANA mean?
- not necessarily mean SLE
- but suggestive IF there are other clinical and lab features to support the diagnosis
- a stronger test is more likely to be clinically significant
43
What is the strength of ANA like?
reported as maximal dilution at which it is still detectable
| eg 1:80 (weak), 1:320, 1:640, 1:1280 (strong)
44
What other tests do you order if ANA is positive?
ENA (extractable nuclear antigens): a panel of 5 autoantibodies
45
What ENAs do you order and what do they indicate?
1. Ro: Lupus or Sjogrens syndrome
2. La: Lupus or Sjogrens syndrome
3. RNP: Lupus or mixed connective tissue disease
4. Smith: Lupus
5. Jo-1: Polymyositis
46
In lupus what antibodies are highly speicifc?
Double stranded (dsDNA) antibodies
47
What is dsDNA used for?
- associated with renal involvement
| - useful for tracking lupus activity over time
48
What are the complement
| levels C3 and C4 like in lupus?
may be ↓ in active lupus
49
How is synovial fluid analysed?
Obtained by aspirating fluid from a joint
50
What are the indications for joint aspiration?
a) Diagnostic: to obtain synovial fluid for analysis
| b) Therapeutic: to relief symptoms (+/- concurrent steroid injection)
51
What are the two main diagnostic uses for aspiration?
1. Suspected septic arthritis
| 2. Diagnosing crystal arthritis
52
How does aspiration help in suspected septic arthritis?
1. gold standard for diagnosis
2. send for MC&S
3. enables causative organism to be identified
4. sensitivities from culture guide antibiotic choice
53
How can the diagnosis of crystal arthritis be made?
aspirating fluid from the affected joint and examining it under a microscope using polarized light
54
How does gout look?
needle shaped crystals with negative birefringence
55
How does pseudogout look?
rhomboid shaped crystals with positive birefringence
56
What is the synovial fluid culture like in septic arthritis and reactive arthritis?
- Septic arthritis: positive
| - Reactive arthritis: sterile
57
What is the antibiotic therapy like in septic arthritis and reactive arthritis?
- Septic arthritis: yes
| - Reactive arthritis: no
58
What is the joint lavage like in septic arthritis and reactive arthritis?
- Septic arthritis: yes (for large joints)
| - Reactive arthritis: no
59
When are X rays done?
first line, cheap, widely available
60
What are CTs done?
more detailed bony imaging
61
When is MRI done?
1. Best visualization of soft tissue structures like tendons and ligaments
2. Best for spinal imaging: can see spinal cord and exiting nerve roots
3. Expensive and time-consuming
62
When is USS done?
1. Like MRI can visualize soft tissue structures.
| 2. Good for smaller joints, less good for deep/large joints like knee or hip
63
When are plain X rays the most useful test?
diagnosing OA
64
What are the radiographic features of OA?
1. Joint space narrowing
2. Subchondral bony sclerosis
3. Osteophytes
4. Subchondral cysts
65
What are the radiographic features of RA?
1. Soft tissue swelling
2. Peri-articular osteopenia
3. Bony erosions
66
When are there bony erosions in RA?
1. established disease
2. aim of modern therapy is to treat EARLY before erosions (permanent damage) has occurred
3. Informatiion from X-rays is limited to bony structures
67
When is US used in RA?
- detecting synovitis
| - US (usually of hands and wrists) can be performed alongside clinical assessment in a dedicated early arthritis clinic
68
What are the us changes in RA?
1. Synovial hypertrophy (thickening)
2. Increased blood flow (seen as doppler signal)
3. May detect erosions not seen on plain X-ray
69
Can MRI be used in RA?
yes but expensive and time-consuming
70
Is there joint space narrowing in RA and OA?
- RA: yes
| - OA: yes
71
Is there subchondral sclerosis in RA and OA?
- RA: no
| - OA: yes
72
Is there osteophytes in RA and OA?
- RA: no
| - OA: yes
73
Is there osteopenia in RA and OA?
- RA: yes
| - OA: no
74
Is there bony erosions in RA and OA?
- RA: yes
| - OA: no
75
What are the radiographic features of gout?
juxta-articular 'rat bite' erosions at the MTPJ of the great toe
76
What are the radiographic features of psoriatic arthritis?
1. Asymmetrical pattern of joint involvement
2. Erosions of IPJs
3. MCPJs not affected (unlike RA)
