rheum diagnostics Flashcards

1
Q

what are the different types of rheumatology diagnostics

A
  1. blood tests
  2. joint(synovial) fluid analysis
  3. imaging tests: xrays, ultrasound,ct,mri
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2
Q

basic blood tests in rheumatology

A
fbc
urea and electrolytes
liver function tests
bone profile
erythrocyte sedimentation rate
c reactive protein
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3
Q

what are the 3 main types of arthritis

A

osteorthritis
inflammatory
septic

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4
Q

what would you expect to see in fbc of inflammatory arthritis

A

low (in anaemia) or normal hb
normal mcv
usually normal wcc
normal/high platelets

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5
Q

what would you expect to see in fbc of osteoarthritis

A

normal hb
normal mcv
normal wcc
normal platelets

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6
Q

what would you expect to see in fbc of septic arthritis

A

usually normal hb
normal mcv
high wcc - leukocytosis
normal/high platelets

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7
Q

why might anaemia and therefore low hb occur in inflammatory arthritis

A

long standing uncontrolled inflammation can suppress bone marrow leading to less production of red cells

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8
Q

what are u&es ?

A

urea
creatinine
sodium
potassium

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9
Q

what does a higher creatinine suggest and why is it relevant to rheum

A

higher cr = worse renal clearance indicating kidney problem

rheum disease can affect kidneys

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10
Q

what can sle do to kidneys

A

can cause lupus nephritis - which is kidney inflammation

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11
Q

what can vasculitis do to kidneys

A

glomerular nephritis

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12
Q

what can chronic inflammation in poorly controlled inflammatory disease cause

A

high levels of serum amyloid (saa) protein leads to saa deposits in organs (aa amyloidosis)

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13
Q

what effects do NSAIDs e.g ibuprofen do to kidneys

A

can cause kidney impairment

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14
Q

what are the lfts

A

bilirubin
alanine aminotransferase
alkaline phosphatase
albumin

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15
Q

why are lfts a relevant test in rheumatology

A

dmards e.g methotrexate can cause liver damage

*patients on methotrexate need regular blood tests (e.g every 8wks)

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16
Q

what is low albumin a sign of?

A

can either reflect problem of synthesis (in liver) or problem of leak from kidney e.g in lupus nephritis

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17
Q

what is pagets disease

A

disease caused by abnormality of high bone turnover

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18
Q

what are the clinical features of pagets disease

A

bone pain, excessive pain growth

fracture through area of abnormal bone

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19
Q

when would you expect the alp to be very high

A

pagets disease of bone

20
Q

what might you see in bone profile of osteomalacia (soft bone due to vit d def)

A

normal/high alp

normal/low ca and po4

21
Q

what is osteoporosis

A

low bone density

22
Q

bone profile seen in osteoporosis

A

usually ca, po4 and alp are normal

23
Q

what are some other reasons esr may be high.

A

elevated immunoglobulin level
paraprotein (myeloma)
anaemia
tends to rise with age

24
Q

what is the rule of thumb in sle

in regards to esr and crp

A

esr usually high but crp normal
exception: crp high in sle if significant synovitis/inflammatory pleural or pericardial effusion
if crp high in lupus - suspect infection

25
Q

what if esr/crp are elevated and there is evidence of inflammatory arthritis what bloods should be done

A

look for 2 types of antibodies in blood:

  • rheumatoid factor: antiIgG antibody
  • cyclic citrullinated peptide antibodies
26
Q

why is ccp helpful

A

more specific thanrf

associated with worse prognosis

27
Q

what are anti nuclear antibodies

A

antibodies directed at nuclear component of cell

28
Q

what is ana use in rheumatology

A

high titre ana in combination with correct clinical features may indicate autoimmune connective tissue diseases e.g sle, sjogrens, scleroderma

29
Q

how can we interpret anas

A

negative test rules out sle

postive test - doesnt necessarily mean sle, other clinical features needed to support diagnosis

30
Q

what to do if ana comes back positive

A

ena test of 5 autoantibodies: ro,la,rnp,smith,jo1

31
Q

which of the 5 autoantibodies would be positive in lupus

A

ro,la,rnp,smith

32
Q

which of the 5 autoantibodies would be positive in sjogrens syndrome

A

ro,la

33
Q

what does positive jo1 on test mean

A

polymyositis

34
Q

why is double stranded dna antibodies a useful test

A

highly specific for lupus, associated with renal involvement, useful for tracking lupus activity over time

35
Q

when are c3 and c4 complement levels useful

A

may be low in active lupus

36
Q

what are the 2 indications for joint aspiration

A

diagnostic - to obtain synovial fluid for analysis

therapeutic - to relieve symptoms

37
Q

how is synovial fluid obtained

A

by aspirating fluid from joint

38
Q

what are the 2 main diagnostic uses for aspiration

A
  1. suspected septic arthritis
    - gold standard for diagnosis
    - send for mc and s
    - enables causative organism to be identified
    - sensitivities from culture guide antibiotic choice
  2. diagnosing crystal arthritis
39
Q

key differences in septic and reactive arthritis

A

sa - positive synovial fluid culture whilst sterile in reactive
antibiotic therapy needed in septic arthritis
joint lavage needed in septic arthritis

40
Q

imaging test in rheum

A

x rays - first line, cheap, widely available
ct scans - more detailed bony imaging
mri - best visualisation of soft tissue, best for spinal imaging, expensive and time consuming
us - like mri good for soft tissue, good for smaller joints, less good for large/deep joints

41
Q

what is the most useful diagnostic test in oa

A

xrays

42
Q

what are radiographic features seen in osteoarthritis

A

joint space narrowing
subchondral bony sclerosis
osteophytes
subchondral cysts

43
Q

what are some radiographic features found on xrays of ra

A

soft tissue swelling
peri articular osteopenia
boney erosions - aim is to treat before erosions

44
Q

us is much better at detecting synovitis. us changes in ra:

A

synovial hypertrophy
increased blood flow - doppler signal
may detect erosions

45
Q

radiographic features of gout

A

juxta articular ‘rat bite’ erosions - at mtpjs