Pathology
This was previously featured in an exam
This was previously featured in an exam
Inflammatory Responses
Question 12 of 19
A patient with suspected systemic lupus erythematosus (SLE) presents to ED with an exacerbation of symptoms. You consult with her rheumatologist who requests that you perform some blood tests for certain autoantibodies. Which of the following antibodies is MOST likely to be positive in SLE:
Answer:
Antinuclear antibodies (ANA) are autoantibodies to the nuclei of your cells. 98% of all people with systemic lupus have a positive ANA test, making it the most sensitive diagnostic test for confirming diagnosis of the disease. Other autoantibodies, such as rheumatoid factor, antiphospholipid antibodies and antimitochondrial antibodies, may also be present in patients with SLE.Plasma Autoantibodies
Pathology / Inflammatory Responses
Last Updated: 1st April 2020
Autoimmune disease can be either organ-specific illnesses (e.g. thyroid disease, type 1 diabetes mellitus, myasthenia gravis) or systemic illnesses (e.g. rheumatoid arthritis (RA), systemic lupus erythematosus (SLE)). The cause of autoimmune damage may be mainly due to either autoantibodies or autoimmune T lymphocytes. Nearly all autoimmune diseases are associated with circulating autoantibodies, which may also be found associated with non-related illnesses and in healthy individuals. Autoantibodies are often detected many years before the onset of disease.
Examples of autoantibodies and their associations include:
- Rheumatology
- Antinuclear antibodies
- Raised ANAs are almost always present in SLE
- It is also associated with drug-induced lupus erythematosus (LE), systemic sclerosis (scleroderma), Sjögren's syndrome, polymyositis and dermatomyositis, mixed connective tissue disorder and autoimmune hepatitis
- It may also be seen in Addison's disease, idiopathic thrombocytopenic purpura (ITP), Hashimoto's thyroiditis, autoimmune haemolytic anaemia and type 1 diabetes mellitus
- Rheumatoid factor
- High levels are associated with RA and Sjögren's syndrome
- Other disease associations include chronic hepatitis, chronic viral infection, tuberculosis, leprosy, leukaemia, dermatomyositis, infectious mononucleosis, systemic sclerosis and SLE
- Antiphospholipid antibodies
- Anticardiolipin antibodies are the most commonly detected antiphospholipid antibodies and are associated with primary antiphospholipid syndrome (also present in some people with SLE)
- Antineutrophil cytoplasmic antibodies (ANCA)
- Associated with necrotising vasculitis and vasculitis associated with rheumatic and inflammatory bowel disease; two main types:
- C-ANCA (cytoplasmic): associated with granulomatosis with polyangiitis (Wegener's granulomatosis), micropolyarterits, Churg-Strauss syndrome, polyarteritis nodosa and RPGN
- P-ANCA (perinuclear): associated with microscopic polyangiitis, Churg-Strauss syndrome, anti-GBM disease, crescenteric glomerulonephritis and granulomatosis with polyangiitis (Wegener's granulomatosis)
- Antinuclear antibodies
- Gastroenterology
- Intrinsic factor antibodies associated with pernicious anaemia
- Parietal cell antibodies associated with autoimmune gastritis
- IgA anti-tissue transglutaminase (anti-tTG), anti-gliadin and endomysial antibodies (EMAs) associated with coeliac disease
- Antimitochondrial antibodies associated with primary biliary cirrhosis
- Anti-smooth muscle antibodies associated with autoimmune hepatitis
- Endocrinology
- Glutamic acid decarboxylase (GAD), islet cell and insulin antibodies associated with type 1 diabetes mellitus
- Anti-thyroid peroxidase (TPO), TSH (thyrotropin) receptor and thyroglobulin (TG) antibodies associated with autoimmune thyroid disease
- Antisperm antibodies associated with immunological infertility
- Steroid cell antibodies associated with Addison's disease and autoimmune gonadal failure
- Neurology
- Acetylcholine receptor antibodies associated with myasthenia gravis
- Antibodies associated with peripheral neuropathy
- Nephrology
- Anti-glomerular basement membrane (GBM) antibodies associated with Goodpasture's syndrome
- Cardiology
- Cardiac muscle antibodies associated with heart failure, myocarditis and dilated cardiomyopathy
- Dermatology
- Intra-epidermal/desmosome antibody (pemphigus antibody) associated with pemphigus
- Basement membrane zone antibody (pemphigoid antibody) associated with pemphigoid
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
