Rheumatology Diagnostics Flashcards
What are the 3 main diagnostic pathways in rheumatology?
Blood tests
Joint fluid analysis
Imaging tests
How often are blood tests needed in rheumatology? If they are, how are they ordered?
They may not be needed if the diagnosis is clear from the history and examination, if they are start with simple ones before ordering fancy ones
What do basic rheumatology blood tests include?
FBC Urea and electrolytes Liver function tests Bone profile ESR CRP
Describe expected Hb, MCV, WCC and PLT in inflammatory arthrtis
Hb= low if anaemic or normal MCV= normal WCC= usually normal PLT= normal or raised
Describe expected Hb, MCV, WCC and PLT in osteoarthritis
Hb=normal
MCV=normal
WCC=normal
PLT=normal
Describe expected Hb, MCV, WCC and PLT in septic arthritis
Hb= usually normal
MCV=normal
WCC= high due to leucocytosis
PLT= normal or high
What is encompassed in urea and electrolytes?
Creatinine
Sodium
Potassium
What does high creatinine indicate?
Worsening renal clearance
Why are urea and electrolytes relevant in rheumatology diagnostics?
Rheumatological disease can effect the kidneys
NSAIDs can cause kidney impairment
Chronic inflammation can lead to serum amyloid a deposits in the kidney
What do LFTs encompass?
Bilirubin
Alanine aminotransferase (ALT)
Alkaline phosphatase (ALP)
Albumin
Why are LFTs relevant in rheumatology diagnostics?
DMARDs can cause liver damage
What do patients on methotrexate need regularly?
Blood tests every 8 weeks (to check LFTs and ensure there isnt liver damage)
What can low albumin indicate?
Problem of synthesis (in liver) or problem of leak from kidney (eg in lupus nephritis)
What does bone profile encompass?
Calcium
Phosphate
Alkaline phosphotase
What diagnostic component is present in both the LFT and bone profile?
ALP
What will ALP levels be in Paget’s disease?
High
What is Paget’s disease?
Disease caused by abnormality of high bone turnover
Describe calcium, phosphate and ALP levels in someone with osteomalacia
Calcium low or normal
Phosphate low or normal
ALP high or normal
What are clinical features of Paget’s disease
Bone pain, excessive pain growth, fracture through area of abnormal bone
Describe calcium, phosphate and ALP levels in someone with osteoporosis
All normal
What are ESR and CRP useful markers of?
Inflammation
What are reasons beside inflammation ESR could be up?
Elevated immunoglobulin level
Paraprotein (myeloma)
Anaemia
Tends to rise with age
What are ESR and CRP in SLE?
ESR is usually high, CRP is usually normal
When may CRP be high in SLE?
If there is significant synovitis or there is an inflammatory pleural or pericardial effusion
What are the 3 main types of arthritis?
Osteoarthritis
Inflammatory
Septic
What are the 2 autoantibodies in RA?
Rheumatoid factor (RF) Cyclic citrullinated peptides (CCP) antibodies
What are anti nuclear antibodies?
Antibodies directed at nuclear component of the cell
Other than in RA, when might ANAs be high?
They increase with age
Sometimes high after infection
When is ANA used in rheumatology?
When you suspect an autoimmune condition and to support the diagnosis, its not helpful if used only to diagnose as a lot of people will have a high ANA
What are clinical manifestations of SLE?
Arthritis Skin rash Mouth ulcers Kidney disease Pleural effusion Pericardial effusion
What are clinical manifestations of Sjorgen’s syndrome?
Dry eyes
Dry mouth
Extra articular features
What are clinical manifestations of polymyositis?
Muscle inflammation
Weakness
High CK
What are clinical manifestations of scleroderma?
Vasculopathy eg Reynaud’s
Skin thickening
Organ fibrosis
How is strength of ANA reported?
As the maximal dilution at which its still detectable
What does a negative ANA mean?
SLE can be ruled out
What does a positive ANA mean?
Doesn’t necessarily mean SLE can be diagnosed but means it is more likely if other clinical features are present
What is done after ANA comes out positive?
Other more specific antibody tests are ordered to see what condition the patient has
What are double stranded DNA antibodies specific to?
Lupus
What antibodies are useful for tracking lupus over time?
Double stranded DNA
What will C3 and C4 levels be in lupus?
Low
What are indications for joint aspiration?
Diagnostic: to obtain synovial fluid for analysis
Therapeutic: to relief symptoms
Why is synovial fluid analysis useful for septic arthritis?
It enables the causative organism to be identified and can guide antibiotic choice
What is synovial fluid analysis used to diagnose?
Crystal arthritis
Is joint lavage used for septic arthritis and reactive arthritis?
It is for septic arthritis but not for reactive
What is the first line imaging in rheumatology
X rays
When is MRI useful for imaging in rheumatology?
When looking at soft tissue in small joints, but its not useful for large joints
What are some radiographic features of osteoarthritis?
Joint space narrowing
Subchondral bony sclerosis
Osteophytes
Subchondral cysts
At what point do erosions occour in RA?
In established disease, the aim is to treat early before erosions occour
What is ultrasound useful for in RA?
Detecting synovitis
Do RA or osteoarthritis have joint space narrowing?
Yes they both do
Do RA or osteoarthritis have subchondral sclerosis?
RA doesnt osteo does
Do RA or osteoarthritis have osteophytes?
RA doesnt osteo does
Do RA or osteoarthritis have osteopenia?
RA does psteo doesn’t
Do RA or osteoarthritis have bony erosions?
RA does, osteo doesn’t
