Rheumatology Investigations

Question 1

what is included in a full blood count

Answer 1

haemoglobin, MCV, neutrophil count, lymphocyte count, eosinophil count, platelet count

Question 2

what is the relevance of haemoglobin

Answer 2

may be low in most inflammatory conditions

may be an indicator of disease activity

may get iron deficiency anaemia with NSAIDs

Question 3

what is the relevance of MCV

Answer 3

may be high in patients on sulfasalazine, methotrexate or azathiprine

low in iron deficiency

Question 4

when is MCV of no significance

Answer 4

of Hb stable and B12 folate and TFTs normal

Question 5

what is the relevance of neutrophil count

Answer 5

may be low in CTD (especially SLE and sjogrens)

neutropenia can be adverse effect of most DMARDs

occasionally raised in inflammatory arthritis

Question 6

what is the relevance of lymphocyte count

Answer 6

may be low in CTD (especially SLE and sjogrens)

reduced by immunosuppressants

indicator of disease activity

Question 7

what is the relevance of eosinophil count

Answer 7

raised in eosinophilic granulomatous with polyangiitis (churg-strauss)

indicator of disease activity

Question 8

what is the relevance of plasma viscosity

Answer 8

high in inflammatory conditions

indicator of disease activity

Question 9

why is there a risk of toxicity in renal impairment with methotrexate

Answer 9

as it is excreted renally

Question 10

what rheumatological disease can cause renal impairment

Answer 10

CTD

Question 11

what is the relevance of LFTs

Answer 11

DMARDS, allopurinol and NSAIDs can cause hepatitis

Question 12

what is the relevance of corrected calcium

Answer 12

hyperparathyroidism may cause pseudogout/ calcium pyrophosphate arthropathy (CPPD)

Question 13

what is the relevance of ferritin

Answer 13

low in iron deficiency
high in anaemia of chronic disease

in presence of iron deficiency can be artificially high in inflammatory disease as also acts as an acute phase reactant

Question 14

what is the relevance of creatine kinase

Answer 14

raised in myositis

indicator of disease activity

may also be raised in muscle trauma and strenuous exercise

Question 15

what is the relevance of uric acid

Answer 15

raised in gout

normal in about 30% of cases of acute gout

may get asymptomatic hyperuricaemia

Question 16

what is the relevance of urine protein/ creatine ratio

Answer 16

may get glomerulonephritis as part of connective tissue disease or vasculitis

Question 17

when do you do a synovial fluid microscopy and culture

Answer 17

suspected septic arthritis or crystal arthritis

Question 18

what is very unlikely if RF negative

Answer 18

extra-articular manifestations of RA

Question 19

who has a worse prognosis: sero negative or positive for RF in RA

Answer 19

sero negative

Question 20

how sensitive and specific is RF for RA

Answer 20

70% sensitive

85% specific

Question 21

how sensitive and specific is anti- CCP for RA

Answer 21

70% sensitive

98% specific

Question 22

who has a worse prognosis: sero negative or positive for anti-ccp in RA

Answer 22

negative

Question 23

how sensitive and specific is anti- nuclear antibody for SLE

Answer 23

98% sensitive 
non specific (13% of adults +ve titre of 1:80- positive in a wide range of diseases inc. RA)

Question 24

what is anti-dsDNA specific for and how specific

Answer 24

95% specific for SLE

Question 25

can anti-dsDNA be used to monitor disease activity

Answer 25

yes

Question 26

what does ENA stand for

Answer 26

extractable nuclear antigens

Question 27

what can anti-RNP be positive in

Answer 27

usually in mixed connective tissue disease can be in SLE

Question 28

what can anti-centromere be positive in

Answer 28

limited systemic sclerosis

Question 29

what can anti-Scl 70 be positive in

Answer 29

diffuse systemic sclerosis

Question 30

what can anti-Ro and anti:La be positive in

Answer 30

primary sjogrens syndrome

Question 31

what can anti-Jo-1 be positive in

Answer 31

inflammatory myositis

Question 32

what can anti-Sm be positive in

Answer 32

very specific for lupus but in UK only in 3% of cases

Question 33

what can anti-cardiolipin antibiodies (ACLA) be positive in

Answer 33

anti-phospholipid syndrome

Question 34

what is there an increased risk of when ACLA is positive

Answer 34

thrombosis or pregnancy loss

Question 35

what is c-ANCA/ anti- PR3 sensitive and specific for

Answer 35

granulomatosis with polyangitis (wegeners granulomatosis)

Question 36

can ANCA be used to monitor disease activity

Answer 36

yes

Question 37

how specific is p-ANCA/ anti-MPO and what is it associated with

Answer 37

less specific than c-ANCA/ anti-PR3 associated with microscopic polyangitis and churg strauss syndrome fluctuates, used to monitor disease activity

Question 38

what is the relevance of complement

Answer 38

low in immune complex vasculitis esp lupus nephritis low in active lupus, used to monitor disease activity

Question 39

what is the baseline imaging for early inflammatory arthritis- what would you expect to see

Answer 39

Xray hands and feet expect to be normal- erosions may indicate poor prognosis

Question 40

what is x ray of hands and feet used to diagnose

Answer 40

OA

Question 41

what imaging for neck pain, especially in RA

Answer 41

cervical spine X ray

Question 42

what is a cervical spine x ray looking for in RA flexion and extension views

Answer 42

atlanto-axial instability/ subluxation

Question 43

why might a thoracic and lumbar spine x ray be done

Answer 43

to look for spondyloarthropathy changes

Question 44

why would you do a High resolution CT chest

Answer 44

if suspect ILD as part of CTD/ RA

Question 45

why would you do a joint ultrasound

Answer 45

to diagnose inflammatory arthropathy if not convinced by clinical synovitis

Question 46

why would you do a MRI of the spine

Answer 46

non radiographic spondyloarthropathy- will show changes earlier than x ray