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Diagnosing Lupus

May 04, 2013 - 0 comments

Diagnosing lupus
Lupus is a difficult disease to diagnose, & can be overlooked, often for years, unless the GP or consultant is alert to it's possibilities.

How do doctors know if you’ve got Lupus?

Your medical history - what you tell the doctor
What they find when we examine you
What the blood tests show
To help distinguish Lupus from other diseases, physicians of the American Rheumatism Association have established a list of 11 abnormalities which, when combined, point to lupus.
To make a diagnosis of Lupus the patient must have had at least FOUR of these 11 manifestations at any time since the onset of the disease.

1 Malar rash fixed red rash over the cheeks   
2 Discoid rash red patches of skin associated with scaling and plugging of the hair follicles   
3 Photosensitivity rash after exposure to sunlight   
4 Mucosal ulcers small sores that occur in mucosal lining of mouth and nose   
5 Serositis inflammation of the delicate tissues covering internal organs and abdominal pain   
6 Arthritis -very common in lupus, pain in the joints   
7 Renal disorders usually detected by routine blood and urine analysis   
8 Neurological disorder seizures or psychosis   
9 Haematological disorder haemolytic anaemia, leukopenia, thrombocytopenia   
10 Immunologic disorder tests on LE cells, anti-DNA and anti-SM antibodies   
11 Anti-Nuclear Antibody (ANA blood test) when found in the blood and the patient is not taking drugs, it is known to cause a positive test for lupus in most cases, but is not necessarily conclusive
The above criteria were laid down by the ACR in 1982. Dr Graham Hughes (St. Thomas' Hospital, London) has since come up with an 'alternative list of criteria'.

What blood tests are done to help diagnose Lupus?

Full Blood Count (FBC) - Detects anaemia, low platelets, low white blood cells
Creatinine and electrolytes - Measures the salts in the blood and gives an idea of kidney function
Liver function tests - Includes measurement of liver enzymes (indicator of liver cell damage). Measures albumin (marker of kidney problem with leakage of the proteins)
ESR (Erythrocyte Sedimentation Rate) - A marker of non-specific inflammation, tends to be raised in lupus
CRP (C-reactive protein) - Another inflammatory marker, but this does NOT usually go up in Lupus
Urine - Measure protein and blood cells in urine (should be none). Identify ‘casts’ (blobs of protein escaped from the bloodstream because the kidneys are leaky)
Blood clotting tests - Tell how ‘sticky’ the blood is. Includes ‘lupus anti-coagulant’
Immunological tests

Blood Tests
  
Regular blood tests are essential to monitor how active the disease is and whether treatment is working.
Tests will include -
Full blood count
Sedimentation rate
Kidney and liver tests [creatinine, liver enzymes]
Tests for protein in urine
Antibodies to double stranded DNA - rising levels often predict a relapse
Complement proteins [C3d]

Monitoring for side effects of drugs

Prednisolone and other steroids
- Blood glucose
- Fats in the blood
- Full blood count (toxic to lymphocytes)
Azathioprine (Imuran)
- Can damage liver - regular liver enzymes tests (can require a biopsy)
- Toxic to bone marrow - regular full blood counts to look at white blood cells (can require a bone marrow biopsy)
- Antibodies (can become very low)
- Enzyme test now available that predicts whether side effects are likely with azathioprine (thiopurine methyltransferase - TPMT)
Cyclophosphamide
- Toxic to white cells - regular full blood counts
- Antibodies (can become very low)
- Urine (can cause bleeding from the bladder)
Cyclosporin and Tacrolimus [FK506]
- Very powerful immunosuppressives
- Can damage kidneys and liver - check kidney and liver function
- Blood levels can be measured in the laboratory to help adjust dose
Lupus is characterized by abnormalities in many laboratory test results. These abnormalities are different for every patient and vary significantly during the course of a patient’s disease.
The serial evaluation of an individual’s tests along with the physician’s observations and the patient’s history determine the diagnosis of SLE, its course, and the treatment regimen. All laboratory values must be interpreted in light of the patient’s present status, other correlating laboratory test results, and coexisting illnesses.
Blood tests used to diagnose and monitor lupus -
Albumin
ANA
ANCA (antineutrophil cytoplasmic antibodies), P-ANCA (perinuclear) C-ANCA (cytoplasmic)
Anti-Cardiolipin (Anti-Phospholipid)
Anti-DNA
Anti-Ro/SS-A
Anti-Sm antibodies
Blood Urea Nitrogen (BUN)
CBC
Complement studies
Cholesterol
CPK
Creatinine
Creatinine Clearance
Differential Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils
ENA (Extractable Nuclear Antigens)
Erythrocyte Sedimentation Rate (Sed Rate, ESR)
Immunoglobulins (IG)
Iron
Rheumatoid Factor
White Blood Count (WBC, Leukocyte count)

Monitoring disease activity of lupus with blood tests
Regular blood tests are essential to monitor how active the disease is and whether treatment is working.
Tests will include -
Full blood count
Sedimentation rate
Kidney and liver tests [creatinine, liver enzymes]
Tests for protein in urine
Antibodies to double stranded DNA - rising levels often predict a relapse
Complement proteins [C3d]

Monitoring for side effects of drugs

Prednisolone and other steroids
- Blood glucose
- Fats in the blood
- Full blood count (toxic to lymphocytes)
Azathioprine (Imuran)
- Can damage liver - regular liver enzymes tests (can require a biopsy)
- Toxic to bone marrow - regular full blood counts to look at white blood cells (can require a bone marrow biopsy)
- Antibodies (can become very low)
- Enzyme test now available that predicts whether side effects are likely with azathioprine (thiopurine methyltransferase - TPMT)
Cyclophosphamide
- Toxic to white cells - regular full blood counts
- Antibodies (can become very low)
- Urine (can cause bleeding from the bladder)
Cyclosporin and Tacrolimus [FK506]
- Very powerful immunosuppressives
- Can damage kidneys and liver - check kidney and liver function
- Blood levels can be measured in the laboratory to help adjust dose

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