Diagnosis of Autoimmune Diseases

Question 1

Tests to confirm autoimmune disease

Answer 1

ANA
ANCA
CK
Rheumatoid factor
Anti-CCP antibody
Complement
FBC
U&Es
LFTs
CRP

Question 2

Types of diagnostic testing for autoimmune disease

Answer 2

Non-specific - inflammatory markers

Disease-specific - Autoantibody testing and HLA typing

Question 3

Non-specific markers of systemic inflammation

Answer 3

ESR
CRP
Ferritin
Fibrinogen
Haptoglobin
Albumin
Complement

Question 4

ANAs

Answer 4

Antinuclear antibodies

Test for this can then identify which part of the nucleus is being targeted by antibodies

Question 5

Rheumatoid Factor (RF)

Answer 5

Commonly found and tested for for rheumatoid arthritis
Not diagnostic of the disease (sensitivity and specificity around 70%)
Can be seen with other diseases in which polyclonal stimulation of B cells is seen such as chronic infection

Question 6

ACPA

Answer 6

Anti-CCP antibody
More specific for RA than RF (around 95% to 70%)
Similar sensitivity to RF (around 70%)
Useful prognostic marker as ACPA positive patients tend to have more severe disease

Question 7

Diagnosing of RA

Answer 7

Combination of symptoms, X-rays and blood tests
High RhF, CCP and elevated ESR and CRP add to probability y of a definitive diagnosis
Early treatment can prevent joint damage and significant morbidity

Question 8

Granulomatosis with polyangitis

Answer 8

Formally known as Wegener’s granulomatosis
Histology: Leukocytic vasculitis, necrotising, granulomatous inflammation
ENT symptoms: Nasal septum perforation, saddle nose deformity, conductive or sensorineural hearing loss, subglottilc anaemia
Eye symptoms: Orbital pseudotumouts, scleritis, episcleritis, uveitis (50%)
Lung symptoms: Nodules, infiltrates or cavitary lessons, alveolar haemorrhage
Kidney symptoms: Segmental necrotising glomerulonephritis
Heart symptoms: Occasional valvular lesion
PNS symptoms: Vasculitic neuropathy (10%)
Systemic symptoms: Mild eosinophilia occasionally

Question 9

Autoimmune liver disease

Answer 9

Part of non-invasive liver disease, performed if liver tests deranged
Anti-mitochondrial Ab specific for primary biliary sclerosis
Anti-smooth muscle and anti-liver/kidney/microsomal Abs found in autoimmune hepatitis

Question 10

Autoantibodies in type I diabetes mellitus

Answer 10

Several types: islet cell, anti-GAD65, antiGAD67, anti-insulinoma antigen 2, insulin autoantibodies (IAAs)
These disappear with progression of disease and total destruction of B islet cells

Question 11

Addison’s disease

Answer 11

Autoantibodies target adrenal cortex

Impairs cortisol production