Rheumatology Diagnostics Flashcards

1
Q

what are the major divisions of arthritis?

A

osteoarthritis

inflammatory arthritis

septic arthritis

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2
Q

what are the bloods for inflammatory arthritis?

A

Hb low (anaemia) or normal

MCV normal

WCC normal

PLT normal or increased

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3
Q

what are the bloods for oesteoarthrits?

A

Hb, MCV, MCC, PLT all normal

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4
Q

what are the blood for septic arthritis?

A

Hb usually normal

MCV normal

WCC increased (leucocytosis)

PLT normal or increased

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5
Q

what does U & E results measure?

A

urea

creatinine

sodium

potassium

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6
Q

what does creatinine show?

A

Higher Cr= worse renal clearance = kidney problems

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7
Q

what rheumatoid diseases can affect the kidneys?

A
  • Systemic lupus erythematous (SLE) -> lupus nephritis
  • Vasculitis -> nephritis
  • Chronic inflammation in poorly controlled inflammatory disease -> high levels of serum amyloid A (SAA) protein -> SAA deposits in organs (AA amyloidosis)
  • Non-steroidal anti-inflammatory drugs (NSAIDs) can cause kidney impairment
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8
Q

what do LFTs measure?

A
  • Bilirubin
  • Alanine aminotransferase (ALT)
  • Alkaline phosphatase (ALP)
  • Albumin
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9
Q

what needs to be done on patients on methotrexate?

A

regular blood tests (Every 8 weeks)

DMARDs (methotrexate) can cause liver damage

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10
Q

what can low albumin indicate?

A

problem of synthesis (in liver)

the problem of a leak from kidney (e.g lupus nephritis)

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11
Q

what does a bone profile indicate?

A
  • Calcium
  • Phosphate (PO4)
  • Alkaline phosphatase (ALP)
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12
Q

why is ALP measured in bone and liver

A

ALP can be found in bone or liver

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13
Q

what is Page’s disease?

A

disease caused by abnormality of high bone turnover

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14
Q

what are the clinical features of paget’s disease?

A

bone pain

excessive pain growth

fracture through area of abnormal bone

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15
Q

what are the bone profile results for osteomalacia?

A

ALP normal or increased

CA and PO4 normal or low

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16
Q

what is osteomalacia?

A

soft bones due to vitamin D deficiency

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17
Q

what is osteoporosis?

A

low bone density

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18
Q

what is the bone profile for osteoporosis?

A

calcium, PO4 and ALP normal?

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19
Q

how is osteoporosis diagnosed?

A

DEXTA scan

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20
Q

what is ESR & CRP?

A

marker of inflammation

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21
Q

why might ESR be raised other than inflammation?

A
  • Elevated immunoglobulin level
  • Paraprotein (myeloma)
  • Anaemia
  • Tends to rise with age
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22
Q

is ESR or CRP more specific for inflammation?

A

CRP

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23
Q

which is more useful ESR or CRP in SLE?

A
  • ESR usually high but CRP normal
  • Exceptions to the rule: CRP high in SLE if there is significant synovitis or there is an inflammatory pleural or pericardial effusion
  • If CRP in lupus, have a low index of suspicion for infection
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24
Q

what are the 2 types of autoantibodies in RA?

A

rheumatoid factor

cyclin citrullinated peptides (CCP) antibodies

25
Q

what is rheumatoid factor?

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
26
Q

what does CCP antibodies show?

A

more specific than RF

worse prognosis associated

27
Q

what are anti-nuclear antibodies?

A
  • Antibodies directed at nuclear component of the cell –
28
Q

when is ANA test ordered?

A
  • only order if suspect autoimmune CT diseases clinically
29
Q

what are the non specific causes of altered ANA?

A
  • Relatively common in general healthy population at low titre (level)
  • Prevalence of ANA increases with age in the general population
  • Sometimes transiently positive following infection
30
Q

what are the rheumatological uses of ANA?

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)
31
Q

what are the signs of SLE?

A
  1. Arthritis/ arthralgia
  2. Skin rash (photosensitive)
  3. Mouth ulcers
  4. Kidney disease
  5. Haematological abnormalities
  6. Pleural effusion
  7. Pericardial effusion
32
Q

what are the signs of Sjogren’s syndrome?

A
  1. Dry eyes
  2. Dry mouth
  3. Extra-articular features
33
Q

what are the signs of scleroderma

A
  1. Vasculopathy (esp Raynaud’s phenomenon)
  2. Skin thickening
  3. Organ fibrosis
34
Q

what are the signs of polymyositis?

A
  1. Muscle inflammation
  2. Weakness
  3. High CK
35
Q

how is ANA interpreted?

A
  • Strength of ANA is reported as maximal dilution at which it is still detectable
  • eg 1:80 (weak), 1:320, 1:640, 1:1280 (strong)
  • Negative test rules out SLE
36
Q

what does negative ANA rule out?

A

SLE

37
Q

what does a positive test suggest?

A
  • Positive test does 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
38
Q

what other tests should be done if ANA is positive?

A

ENA: panel of 5 autoantibodies

dsDNA (double stranded DNA antibodies)

complement C3 and C4

39
Q

what are the ENA tests and what diseases do they suggest?

A
  • Ro- Lupus or Sjogrens syndrome
  • La- lupus or Sjogren’s syndrome
  • RNP- lupus or mixed connective tissue disorder
  • Smith- lups
  • Jo-1- Polymyositis
40
Q

what is dsDNA useful for?

A
  • highly specific for lupus
  • associated with renal involvement
  • useful for tracking lupus activity over time
41
Q

what is complement C4 and C3 useful for?

A

may be decreased in active lupus

42
Q

how is synovial fluid obtained?

A

aspiration fluid from a joint

43
Q

what are the indications for joint aspiration?

A
  • diagnostic: to obtain synovial fluids for analysis
  • therapeutic: to relieve symptoms (+/- concurrent steroid injections)
44
Q

what are the diagnostic uses of synovial fluid analysis?

A

suspected septic arthritis

diagnosing crystal arthritis

45
Q

how is synovial fluid used for septic arthritis?

A
  • gold standard for diagnosis
  • send for MC&S
  • enables causative organism to be identified
  • sensitivities from culture guide antibiotic choice
46
Q

how is synovial fluid used for crystal arthritis?

A
  • Gout and pseudogout
  • Aspiration and examining under microscope using polarised light
  • Gout: needle shaped with negative birefringence
  • Pseudogout: rhomboid shaped with positive birefringence
47
Q

what are the differences in septic arthritis and reactive arthritis?

A
  • Synovial fluid
    • SA= positive
    • RA= sterile
  • Antibiotic therapy
    • SA= yes
    • RA= no
  • Joint lavage
    • SA= yes- for large joints
    • RA= no
48
Q

what is the first line imaging in rheumatology?

A

X-rays: first-line, cheap, widely available

49
Q

why are MRI useful in rheumatology?

A
  • Best visualization of soft tissue structures like tendons and ligaments
  • Best for spinal imaging: can see spinal cord and exiting nerve roots
  • Expensive and time-consuming
50
Q

when is ultrasound useful in rheumatology?

A
  • Like MRI can visualize soft tissue structures.
  • Good for smaller joints, less good for deep/large joints like knee or hip
51
Q

what are the x-ray findings for osteoarthritis?

A
  • Plain X-rays remain the most useful test in the diagnosis of OA
  • Radiographic features of osteoarthritis:
    • Joint space narrowing (bone touching bone)
    • Subchondral bony sclerosis
    • Osteophytes
    • Subchondral cysts
52
Q

what is the ray finding in Rheumatoid arthritis?

A
  • Soft tissue swelling
  • Peri-articular osteopenia
  • Bony erosions- established disease occurance
53
Q

what is the aim of treatment of RA?

A

treat early before erosions (permanent damage) occur

54
Q

what are the US changes in RA?

A
  • Synovial hypertrophy (thickening)
  • Increased blood flow (seen as doppler signal)
  • May detect erosions not seen on plain X-ray
55
Q

what are the differences in radiographic changes between RA and osteoarthritis?

A
56
Q

what does joint space narrowing indicate?

A
  • articular cartilage loss
    • In RA is secondary damage due to synovitis
    • In OA is primary abnormality
57
Q

what are osteophytes in different locations called?

A
  • Osteophytes at the distal interphalangeal joints= Heberden’s nodules,
  • at proximal inter-phalangeal joints= Bouchard’s nodules
58
Q

what is a common early radiographic sign of inflammatory arthritis in any cause?

A

juxta-articular osteopenia

59
Q

where do bone erosions initially occur?

A

at the margins of the joint where the synovium is in direct contact with bone (the bare area)