Rheumatoid Diagnostics Flashcards by Meley Gdey

rheumatology diagnostics can be divided into?

blood tests
joint (synovial) fluid analysis
imaging: x-rays, ultrasound, CT, MRI

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list ‘basic’ rheumatology blood tests

full blood count
urea and electrolytes
liver function tests
bone profile
erythrocyte sedimentation rate
c-reactive protein

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typical FBC in inflammatory arthritis

Hb: decreased/normal
MCV: normal
WCC: usually normal
platelets: normal or ^

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typical FBC in osteoarthritis

Hb: normal
MCV: normal
WCC: normal
platelets: normal

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typical FBC in septic arthritis

Hb: normal
MCV: normal
WCC: increased
platelets: normal/increased

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FBC includes?

Hb
MCV
WCC
platelet count

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U&E includes?

urea
creatinine
sodium
potassium

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higher creatinine indicates?

worse renal clearance > kidney issues

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give examples of how rheumatological diseases can affect the kidneys

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)

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what drug class can cause kidney impairment?

NSAIDs

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liver function tests include?

bilirubin
alanine aminotransferase
alkaline phosphatase

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relevance of LFTs in rheumatological diseases

DMARDs can cause liver damage

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low albumin can indicate?

reflect problem of synthesis (in liver) or problem of leak from kidney (eg in lupus nephritis)

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bone profile includes?

calcium
phosphate
alkaline phosphatase

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bone profile of Paget’s disease

increased ALP

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bone profile in osteomalacia

ALP normal or ^, Ca and PO4 normal or decreased

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bone profile in osteoporosis

usually calcium, PO4 and ALP normal

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ESR and CRP are useful markers for?

inflammation

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increased ESR can be due to?

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

typical ESR and CRP for SLE

ESR high

CRP normal

when is CRP high in SLE?

if there is significant synovitis or there is an inflammatory pleural or pericardial effusion

what two types of autoantibodies are found in the blood of rheumatoid arthritis?

rheumatoid factor

cyclic citrullinated peptides (CCP) antibodies

what is rheumatoid factor?

Antibodies that recognize the Fc portion of IgG as their target antigen typically IgM antibodies i.e. IgM anti-IgG antibody

is CCP more or less specific than rheumatoid factor?

more specific

cyclic citrullinated peptides (CCP) antibodies are associated with?

worse prognosis

anti-nuclear antibodies in general population

prevalence increases w/ age sometimes transiently +ve following infection relatively common at low level in gen pop

use of ANA in rheumatology

High titre ANA in combination with the correct clinical features may indicate one of the autoimmune connective tissue diseases

list autoimmune connective tissue diseases

SLE scleroderma polymyositis Sjogren's syndrome

clinical features of SLE

``` Arthritis Skin rash Mouth ulcers Kidney disease Haematological Pleural effusion Pericardial effusion ```

clinical features of scleroderma

Vasculopathy (esp. Raynaud’s phenomenon) Skin thickening Organ fibrosis

clinical features of polymyositis

Muscle inflammation Weakness High CK

clinical features of Sjogren's syndrome

Dry eyes Dry mouth Extra-articular features

ANA interpretation

Strength of ANA is reported as maximal dilution at which it is still detectable -ve rules out SLE +ve doesn't necessarily mean SLE, suggestive IF there are clinical + lab features to support the diagnosis

If ANA is +ve, other tests to order?

``` ENA (extractable nuclear antigens): a panel of 5 autoantibodies Double stranded (dsDNA) antibodies ```

ENA includes?

``` Ro > Lupus, Sjogrens La > Lupus, Sjogrens RNP > Lupus or mixed connective tissue disease Smith > Lupus Jo-1 > Polymyositis ```

Double stranded (dsDNA) antibodies test

highly specific for lupus, associated with renal involvement, useful for tracking lupus activity over time Complement levels C3 and C4: may be ↓ in active lupus

how is synovial fluid obtained for analysis?

aspirating fluid from a joint

indications for joint aspiration

Diagnostic: to obtain synovial fluid for analysis Therapeutic: to relief symptoms (+/- concurrent steroid injection)

two main diagnostic uses for aspiration?

suspected septic arthritis | diagnosing crystal arthritis

diagnosis of crystal arthritis is made by?

aspirating fluid from the affected joint and examining it under a microscope using polarized light

gout vs pseudogout crystal arthritis

gout: needle shaped crystals with negative birefringence pseudogout: rhomboid shaped crystals with positive birefringence

septic arthritis vs reactive arthritis key differences

synovial fluid culture: SA +ve, RA sterile antibiotic therapy: SA yes, RA no joint lavage: SA yes, RA no

imaging for rheumatology

x-rays CT MRI ultrasound

radiographic (x-ray) features in osteoarthritis

Joint space narrowing Subchondral bony sclerosis Osteophytes Subchondral cysts

radiographic (x-ray) features in rheumatoid arthritis

Soft tissue swelling Peri-articular osteopenia Bony erosions

ultrasound features in rheumatoid arthritis

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

radiographic (x-ray) features in psoriatic arthritis

asymmetrical pattern erosions of interphalangeal joints MCPJs not affected