RHEUMATOLOGY DIAGNOSTICS

Question 1

What are the 3 different types of investigations that can be done in rheumatology?

Answer 1

Blood tests
Joint (synovial) fluid analysis
Imaging (Xrays, ultrasound, CT, MRI)

Question 2

What are the basic rheumatology blood tests that you should always order first before any fancy ones?

Answer 2

Full blood count (FBC)
Urea and electrolytes (U&E)
Liver function tests (LFT)
Bone profile
Erythrocyte sedimentation rate (ESR)
C-reactive protein (CRP)

Question 3

What tests make up a FBC?

Answer 3

Haemoglobin (Hb)
Mean cell volume (MCV)
White cell count (WCC)
Platelet count (PLT)

Question 4

What does a FBC for a patient with inflammatory arthritis look like?

Answer 4

Hb: Low (anaemia) or normal
MCV: Normal (normocytic anaemia)
WCC: Usually normal
PLT: Normal or high (chronic inflammation)

Question 5

What does a FBC for a patient with osteoarthritis look like?

Answer 5

Hb: Normal
MCV: Normal
WCC: Normal
PLT: Normal

Question 6

What does a FBC for a patient with septic arthritis look like?

Answer 6

Hb: Usually normal (acute so hasn’t had time to drop)
MCV: Normal
WCC: High (usually neutrophils)
PLT: Usually normal or high (marked inflammation)

Question 7

What tests make up a urea and electrolytes (U&E)?

Answer 7

Urea
Creatinine
Sodium
Potassium

Question 8

What does a high creatinine indicate?

Answer 8

Worse renal clearance indicating problem with kidneys

Question 9

Why is it important to do a U&E exam on a patient with rheumatological disease and give examples?

Answer 9

Rheumatological diseases can affect the kidneys:
- SLE (lupus nephritis)
- Vasculitis (glomerular nephritis)
- Chronic inflammation –> high serum amyloid A (SAA) –>
SAA deposits in organs (AA amyloidosis) –> renal
damage

NSAIDs can cause renal impairment

Question 10

What tests make up the LFTs?

Answer 10

Bilirubin
Alanin aminotransferase (ALT)
Alkaline phosphatase (ALP)
Albumin

Question 11

Why is it important to do LFTs on a patient with rheumatological disease?

Answer 11

DMARDs (e.g. methotrexate) can cause liver damage

Question 12

What does a low albumin suggest?

Answer 12

Problem with synthesis in liver
or
Problem with kidneys causing leak

Question 13

What is tested in a bone profile?

Answer 13

Calcium
Phosphate
Alkaline phosphatase (ALP)

Question 14

What will be raised in patients with Paget’s disease of bone?

Answer 14

Alkaline phosphatase (ALP)

Question 15

What is Paget’s disease of bone and what are its clinical features/how it presents?

Answer 15

Disease caused by abnormality of high bone turnover

Bone pain, excessive bone growth, fracture through area of abnormal bone

Question 16

How will an osteomalacia patient’s bone profile look?

Answer 16

ALP: normal or high
Ca: normal or low
PO4: normal or low

Question 17

How will an osteoporosis patient’s bone profile look?

Answer 17

ALP: normal
Ca: normal
PO4: normal

Question 18

What are ESR and CRP markers for?

Answer 18

Inflammation

CRP more specific than ESR

Question 19

What are some reasons other than inflammation that can cause ESR to be elevated?

Answer 19

Elevated immunoglobulin level
Paraprotein (myeloma)
Anaemia
Rises with age

Question 20

In a patient with SLE, how will their ESR and CRP look?

Answer 20

ESR high, CRP normal

CRP can be high sometimes if there is significant synovitis or an inflammatory pleural/pericardial effusion

If CRP is low in SLE, have a low index of suspicion for infection

Question 21

What are ANA and why is it useful?

Answer 21

Anti-nuclear antibodies
Directed at nuclear component of cell

High amount of ANA in combination with correct clinical features indicates an autoimmune connective tissue disorder (SLE, Sjorgren’s, scleroderma)

Question 22

How are ANA levels reported?

Answer 22

Reported as a maximal dilution at which it is still detectable:
- 1:80 (weak), 1:1280 (strong)

Question 23

If you suspect a patient has SLE and they test negative for ANA what does it mean?

Answer 23

Patient doesn’t have SLE

Question 24

If ANA is positive what other tests should you order and what do positive results for each indicate?

Answer 24

Extractable nuclear antigens (ENA): a panel of 5
autoantibodies
- Ro (Lupus/Sjogren’s)
- La (Lupus/Sjogren’s)
- RNP (Lupus/mixed connective tissue disorder)
- Smith (Lupus)
- Jo-1 (Polymyositis)

dsDNA antibodies: Specific for SLE
Complement C3 and C4 levels (may be low in SLE)

Question 25

What are the reasons for performing a joint aspiration?

Answer 25

To obtain synovial fluid for analysis

Therapeutic to relieve symptoms

Question 26

For what conditions is joint analysis done?

Answer 26

Suspected septic arthritis

Diagnosing crystal arthritis

Question 27

What are the differences between septic and reactive arthritis?

Answer 27

Synovial fluid culture:

• Septic arthritis +ve
• Reactive arthritis sterile

Antibiotic therapy:

• Septic arthritis - yes
• Reactive arthritis - no

Joint lavage:

• Septic arthritis - yes for large joints
• Reactive arthritis - no

Question 28

What are the imaging techniques used in rheumatology and give reasons for using each

Answer 28

X-rays: first line, cheap, widely available
CT scans: more detailed bony imaging
MRI: best for soft tissue e.g. tendons/ligaments and spinal imaging
Ultrasound: like MRI but goof for smaller joints and worse for deep/large joints

Question 29

What are the radiographic features of osteoarthritis?

Answer 29

Joint space narrowing
Subchondral bony sclerosis
Osteophytes
Subchondral cysts

Question 30

What are the radiographic features of RA?

Answer 30

Soft tissue swelling
Peri-articular osteopenia
Bony erosions
Joint space narrowing

X-rays only show bony information which isn’t that helpful in early RA

Question 31

What are the features seen via ultrasound for a patient with RA?

Answer 31

Synovial hypertrophy
Increased blood flow (doppler signal)
Erosions not seen on plain X-ray

Much better than X-ray at detecting synovitis

Question 32

What imaging is done for RA?

Answer 32

X-ray
Ultrasound
MRI

Question 33

What are the radiographic changes in RA compared to OA?

Answer 33

Joint space narrowing:
- RA yes, OA yes

Subchondral sclerosis:
- RA no, OA yes

Osteophytes:
- RA no, OA yes

Osteopenia:
- RA yes, OA no

Bony erosions:
- RA yes, OA no

Question 34

What radiographic features can be seen in a patient with gout?

Answer 34

After time, rate-bite erosions at the MTPJ of the great toe

Question 35

What radiographic features can be seen in a patient with psoriatic arthritis?

Answer 35

Asymmetrical joint involvement
Erosions of IPJs
MCPJs not affected (unlike RA)

Question 36

What are Heberden’s/Bouchard’s nodes?

Answer 36

In OA:

• Heberden’s are osteophytes at distal IPJs
• Bouchard’s are osteophytes at proximal IPJs