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Flashcards in Rheumatology Diagnositics Deck (76)
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1
Q

What are the different types of rheumatology diagnostics?

A
  1. Blood tests
  2. Join (synovial) fluid analysis
  3. 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
  1. Osteoarthritis (degenerative arthritis)
  2. Inflammatory arthritis (main type RA)
  3. 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
  1. Bilirubin
  2. Alanine aminotransferase (ALT)
  3. Alkaline phosphatase (ALP)
  4. . 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
  1. Calcium
  2. Phosphate (PO4)
  3. . 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
  1. 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
  1. 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
Q

What are two useful markers of inflammation?

A

ESR and CRP

26
Q

When can ESR be elected but not necessarily form inflammation?

A
  1. Elevated immunoglobulin level
  2. Paraprotein (myeloma)
  3. Anaemia
  4. Tends to rise with age
27
Q

What is more specific for inflammation?

A

CRP

28
Q

What are the rule of thumb with CRP and ESR in SLE?

A
  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
Q

What are the two types of antibodies found in the blood of RA patients?

A
  1. Rheumatoid factor

2. Cyclic Citrulinated peptides (CCP) antibodies

30
Q

What is RF?

A
  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
Q

What are CCP antibodies?

A
  1. More specific than RF

2. Associated with worse prognosis

32
Q

What are anti-nuclear antibodies? (ANA)

A

antibodies directed at nuclear component of the cell

33
Q

How specific are ANA?

A

Non-specific

34
Q

Are ANA common?

A
  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
Q

When is ANA used in rheumatology diagnosis?

A

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
Q

What are some autoimmune connective tissues diseases?

A
  1. SLE
  2. Scleroderma
  3. Sjogren’s syndrome
  4. Polymyositis
37
Q

What are the features of SLE?

A
  1. Arthritis
  2. Skin rash
  3. Mouth ulcers
  4. Kidney disease
  5. Haematological
  6. Pleural effusion
  7. Pericardial effusion
38
Q

What are the features of scleroderma?

A
  1. Vasculopathy (esp. Raynaud’s phenomenon)
  2. Skin thickening
  3. Organ fibrosis
39
Q

What are the features of Sjogren’s syndrome?

A
  1. Dry eyes
  2. Dry mouth
  3. Extra-articular features
40
Q

What are the features of polymyositis?

A
  1. Muscle inflammation
  2. Weakness
  3. High CK
41
Q

What does a negative tests of Anti-nuclear antibodies (ANA) rule out?

A

SLE

42
Q

What does a positive test of ANA mean?

A
  • 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
Q

What is the strength of ANA like?

A

reported as maximal dilution at which it is still detectable

eg 1:80 (weak), 1:320, 1:640, 1:1280 (strong)

44
Q

What other tests do you order if ANA is positive?

A

ENA (extractable nuclear antigens): a panel of 5 autoantibodies

45
Q

What ENAs do you order and what do they indicate?

A
  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
Q

In lupus what antibodies are highly speicifc?

A

Double stranded (dsDNA) antibodies

47
Q

What is dsDNA used for?

A
  • associated with renal involvement

- useful for tracking lupus activity over time

48
Q

What are the complement

levels C3 and C4 like in lupus?

A

may be ↓ in active lupus

49
Q

How is synovial fluid analysed?

A

Obtained by aspirating fluid from a joint

50
Q

What are the indications for joint aspiration?

A

a) Diagnostic: to obtain synovial fluid for analysis

b) Therapeutic: to relief symptoms (+/- concurrent steroid injection)

51
Q

What are the two main diagnostic uses for aspiration?

A
  1. Suspected septic arthritis

2. Diagnosing crystal arthritis

52
Q

How does aspiration help in suspected septic arthritis?

A
  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
Q

How can the diagnosis of crystal arthritis be made?

A

aspirating fluid from the affected joint and examining it under a microscope using polarized light

54
Q

How does gout look?

A

needle shaped crystals with negative birefringence

55
Q

How does pseudogout look?

A

rhomboid shaped crystals with positive birefringence

56
Q

What is the synovial fluid culture like in septic arthritis and reactive arthritis?

A
  • Septic arthritis: positive

- Reactive arthritis: sterile

57
Q

What is the antibiotic therapy like in septic arthritis and reactive arthritis?

A
  • Septic arthritis: yes

- Reactive arthritis: no

58
Q

What is the joint lavage like in septic arthritis and reactive arthritis?

A
  • Septic arthritis: yes (for large joints)

- Reactive arthritis: no

59
Q

When are X rays done?

A

first line, cheap, widely available

60
Q

What are CTs done?

A

more detailed bony imaging

61
Q

When is MRI done?

A
  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
Q

When is USS done?

A
  1. Like MRI can visualize soft tissue structures.

2. Good for smaller joints, less good for deep/large joints like knee or hip

63
Q

When are plain X rays the most useful test?

A

diagnosing OA

64
Q

What are the radiographic features of OA?

A
  1. Joint space narrowing
  2. Subchondral bony sclerosis
  3. Osteophytes
  4. Subchondral cysts
65
Q

What are the radiographic features of RA?

A
  1. Soft tissue swelling
  2. Peri-articular osteopenia
  3. Bony erosions
66
Q

When are there bony erosions in RA?

A
  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
Q

When is US used in RA?

A
  • detecting synovitis

- US (usually of hands and wrists) can be performed alongside clinical assessment in a dedicated early arthritis clinic

68
Q

What are the us changes in RA?

A
  1. Synovial hypertrophy (thickening)
  2. Increased blood flow (seen as doppler signal)
  3. May detect erosions not seen on plain X-ray
69
Q

Can MRI be used in RA?

A

yes but expensive and time-consuming

70
Q

Is there joint space narrowing in RA and OA?

A
  • RA: yes

- OA: yes

71
Q

Is there subchondral sclerosis in RA and OA?

A
  • RA: no

- OA: yes

72
Q

Is there osteophytes in RA and OA?

A
  • RA: no

- OA: yes

73
Q

Is there osteopenia in RA and OA?

A
  • RA: yes

- OA: no

74
Q

Is there bony erosions in RA and OA?

A
  • RA: yes

- OA: no

75
Q

What are the radiographic features of gout?

A

juxta-articular ‘rat bite’ erosions at the MTPJ of the great toe

76
Q

What are the radiographic features of psoriatic arthritis?

A
  1. Asymmetrical pattern of joint involvement
  2. Erosions of IPJs
  3. MCPJs not affected (unlike RA)