Lupus - Blood Tests

Everything You Need to Know About Medical Tests

What blood tests are done to help diagnose & monitor Lupus?

Albumin - Normal Range=3.4-4.7 g/dL. Major component of plasma proteins, influenced by nutritional state, hepatic function, renal function, various diseases. Serum albumin gives an indication of severity in chronic liver disease.

ANA (Antinuclear Antibodies) - Normal Range = < 1:20. A blanket term for lots of different antibodies that bind to the nuclei of cells. Not all types of anti-nuclear antibody are associated with Lupus. ANA is high in - 1/3-3/4 of people over age 65 (usually in low titers), systemic lupus erythematosus (98%), drug-induced lupus (100%), Sjogren's Syndrome (80%), rheumatoid arthritis (30-50%), scleroderma (60%), mixed connective tissue disease (100%), Felty's syndrome, mononucleosis, hepatic or biliary cirrhosis, hepatitis, leukemia, myasthenia gravis, dermatomyositis, polymyositis, chronic renal failure. A negative ANA test does not completely rule out SLE, but alternative diagnoses should be considered. Pattern of staining of ANA may give some clues to diagnoses, but since the pattern also changes with serum dilution, it is not routinely reported. Only the rim (peripheral) pattern is highly specific (for SLE). More information...
A positive test means - Most patients with lupus will have a positive ANA test at some time in the course of their disease. Many normal healthy people also have positive ANA tests. A positive test, in a patient with lupus symptoms, means that lupus is a possible diagnosis.
A negative test means - If the ANA is negative it can mean that the patient does not have lupus, or their lupus is in remission. However, a small number of lupus patients never have a positive ANA test, & some can take a while for the ANA test to become positive.

ANCA (antineutrophil cytoplasmic antibodies), P-ANCA (perinuclear) C-ANCA (cytoplasmic) - Normal Range = none present. ANCA is the antibody to white cells. It is found in approx 20% lupus patients, lupus specificity is poor. C-ANCA suggests a systemic vasculitis disease, and is rarely seen in patients with lupus. P-ANCA is most seen in necrotizing, crescentic glomerulonephritis and polyarteritis nodosa. P-ANCA is found in some lupus patients.

Anti-Cardiolipin (Anti-Phospholipid) - Normal Range for anti-IgG = 0 - 20 GPL; Normal Range for anti-IgM = 0 - 10 MPL. It is the antibody to the cell membrane. Found in approx 33% lupus patients, lupus specificity is fair. Antibodies to cardiolipin have been associated with an incresased incidence of vascular thrombosis, thrombocytopenia and recurrent fetal loss in patients with SLE. Increased in: SLE, some connective tissue diseases, and in Antiphospholipid Syndrome (Hughes Syndrome). Patients with acute and chronic infections (including syphilis, HIV, Lyme disease) may also have increased anti-cardiolipin antibodies.

Anti-DNA - Normal Range = < 1:10 titer. Antibody to cell nucleus. It is increased in Systemic lupus erythematosus (50 %) & is highly specific to SLE. Anti-ds-DNA antibody is not found in drug-induced lupus. Titers of anti-ds-DNA correlate well with disease activity and with occurrence of glomerulonephritis.
A positive test means - In a person with lupus symptoms, a positive test almost always means that lupus is present. However, the test can also be positive in some patients with rare diseases.
A negative test means - A negative test does not mean that lupus is not present.

Anti-Ro/SS-A - Normal Range = Negative. It is positive in Primary Sjogren's syndrome (70%), SLE (30%), rheumatoid arthritis (10%). Patients with antibodies to SS-A may have a negative ANA test. Lupus specificity is fair.
A positive test means -In pregnant women, it can cause the condition known as neonatal lupus. Approx. one quarter of the women who have this antibody, will have a child who develops neonatal lupus.
A negative test means - If both this test and the anti-La/SSB test are negative, the child of a pregnant woman will not develop neonatal lupus.

Anti-Sm antibodies - An antibody that binds to proteins in the nucleus of cells. Rare in UK; mainly found in West Indians with SLE. Not found in any other diseases, only in SLE.
A positive test means - A positive test usually means that lupus is present.
A negative test means - Does not mean that lupus is not present. Most people with lupus have either anti-DNA or anti-Sm antibodies.

Blood Urea Nitrogen (BUN) - Normal Range = 8-20 mg/dL . It is increased in renal failure (acute or chronic), urinary tract obstruction, dehydration, shock, burns, CHF, gastrointestinal bleeding. Drugs with renal toxicity, eg, gentamicin. It is decreased in hepatic failure, nephrotic syndrome, cachexia (low-protein and high-carbohydrate diets).

C3 (complement) - Normal Range = 64-166 mg/dL. . Most diseases with immune complexes will show decreased C3 levels. It is increased in many inflammatory conditions including rheumatoid arthritis, SLE, etc. It is decreased in many conditions including SLE, Sjogren's, rheumatoid arthritis.

C4 (complement) - Normal Range = 15-45 mg/dL. It is decreased in SLE, rheumatoid arthritis, congenital deficiency. Congenital C4 deficiency occurs with an SLE-like syndrome.

Complement studies - Complement (which comes in over 20 varieties) is important in getting rid of bacteria. Deficiency of certain complement molecules [especially C2, C4] increases the risk of developing SLE; these deficiencies run in families, ie can be inherited. Complement is also used up when SLE is active, because of the damage to tissues; this can be measured by C3d
A positive test means - If the levels of complement are low, it means the body is undergoing a severe immune reaction. Although lupus is one cause, there are many others.
A negative test means - Normal levels of complement mean that lupus inflammatory kidney disease is unlikely. However, other types of kidney disease can still occur.

CH50 (complement) - Normal Range = Laboratory-specific U/mL. Measures the overall function of complement.

Cholesterol - Normal Range = Desirable < 200; Borderline 200-239; High risk > 240 mg/dL. Cholesterol level is determined by lipid metabolism, which is in turn influenced by heredity, diet, and liver, kidney, thyroid, and other endocrine organ functions.

Creatinine - Normal Range = 0.6-1.2 mg/dL. It is increased in acute or chronic renal failure; urinary tract obstruction, nephrotoxic drugs. It is decreased in reduced muscle mass, possible drug effect. Measures the salts in the blood and gives an idea of kidney function
A positive test means - Creatinine levels rise when kidney function fails; creatinine clearance falls.
A negative test means - Normal levels mean that kidney function is normal, but do not mean that everything about the kidney is normal.

CRP (C-reactive protein) - An inflammatory marker, but this does NOT usually go up in Lupus

Differential Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils - Normal Range = 1.8-6.8 K/mL; 0.9-2.9 K/mL; 0.1-0.6 K/mL; 0-0.4 K/mL ;0-0.1 K/mL; 0-0.2 K/mL. Increased neutrophils suggests infection (bacterial or early viral, rarely leukemia), acute stress, acute and chronic inflammations. Increased lymphocytes suggest viral infection (especially, infectious mononucleosis, pertussis), chronic infection, drug and allergic reactions, autoimmune disease. Decreased lymphocytes suggest immune deficiency syndrome. Increased monocytes suggests inflammation, infection. Decreased monocytes- depleted in overwhelming bacterial infection. Increased eosinophils suggests allergic states, drug sensitivity reaction, skin disorders, tissue invasion by parasites. Decreased eosinophils suggests acute and chronic inflammation, stress, drugs: steroids. Increased basophils suggests hypersensitivity reactions, drugs.

ENA (Extractable Nuclear Antigens) - These are other antibodies to proteins in the nuclei.
- Includes anti-Sm
- anti-Ro (especially associated with lupus skin disease, heartblock in neonates and Sjögrens syndrome. It can 'leak' across the placenta and lead to slow heartbeat in the developing foetus: this can require a 'blood change' as soon as the baby is born.)
- anti-La (SLE, Sjögrens syndrome)
- anti-RNP (if present with antibodies to DNA, then diagnosis is SLE, if present alone, then diagnosis is mixed connective tissue disease, MCTD)
- Anti-Scl70 (systemic sclerosis)
- Anti-Jol (polymyositis)
- And others

Erythrocyte Sedimentation Rate (Sed Rate, ESR) - Normal Range = Male: < 10. Female: < 15. A marker of non-specific inflammation, tends to be raised in lupus. Increased in infections (osteomyelitis, pelvic inflammatory disease [75%]), inflammatory disease (temporal arteritis, polymyalgia rheumatica, rheumatic fever), anemia, pregnancy, chronic renal failure, GI disease (ulcerative colitis, regional ileitis). Decreased in congestive heart failure, drugs (high dose corticosteroids). Low value of no diagnostic significance. ESR is higher in women and older persons.

Full Blood Count (FBC) - Detects anaemia (low red cell count), low platelets, low white blood cells

Glucose - Normal Range = 60-115 mg/dL. Increased in diabetes mellitus, Cushing's syndrome (10-15%), chronic pancreatitis (30%) Drugs - corticosteroids, phenytoin, estrogen, thiazides. Diagnosis of diabetes mellitus is consistent with a fasting plasma glucose >140 mg/dL on more than one occasion. Hypoglycemia is defined as glucose <50 mg/dL in men and <40 mg/dL in women.

Haemoglobin - Normal Range = Male: 13.6-17.5 Female: 12.0-15.5.

Immunoglobulins (IG) - Normal Range = IgA: 78-367 mg/dL. IgG: 583-1761 mg/dL. IgM: 52-335 mg/dL. IgG increased in- Polyclonal: Autoimmune diseases (eg, SLE, RA), sarcoidosis, chronic or recurrent infections. IgA increased in- Polyclonal: Chronic liver disease, chronic infections (especially of the GI and respiratory tracts). IgG decreased in- Immunosuppressive therapy. IgM decreased in- Immunosuppresive therapy.

Iron - Normal Range = 50-175 µg/dL.

LE cells - An old-fashioned test: it detected antibodies to histones (proteins that support the DNA). These anti-histone antibodies are often found when the Lupus is triggered by drugs

Liver function tests - Includes measurement of liver enzymes. Measures albumin (may indicate a kidney problem)

Platelet Count - Normal Range = 150-450 X 10 3/uL. Platelets are a type of blood cell that helps in clotting. They are used up in severe clotting, and are reduced by antibodies to platelets.

Rheumatoid Factor - Normal Range = Negative (<1:16). Positive in rheumatoid arthritis (75-90%), Sjogren's (80-90%), scleroderma, dermatomyositis, SLE (30%), sarcoidosis, Waldenstrom's macroglobulinemia. Drugs: methyldopa, others. Low titer can be found in healthy older patients (20%). A positive RF test is only one of several criteria needed to make the diagnosis of rheumatoid arthritis.

False positive test for syphilis - Not done normally now; known that that this test picks up antibodies to phospholipids (anti-cardiolipin antibodies, lupus anti-coagulant). Anti-phospholipid antibodies are found in SLE and in Hughes’ syndrome

Uric Acid - Normal Range = Males: 2.4-7.4 Females 1.4-5.8 mg/dL. Increased in renal failure, gout, myeloproliferative disorders (leukaemia, lymphoma, myeloma, polycythemia vera), psoriasis.

White Blood Count (WBC, Leukocyte count) - Normal Range = 3.4-10 K/µL. Increased in infection, inflammation, haematologic malignancy, leukaemias (AML, ALL, CML, CLL), lymphoma. Drugs: corticosteroids. Decreased in Aplastic anaemia (decreased production), B12 or folate deficiency (maturation defect), sepsis (decreased survival). Drugs: phenothiazines, chloramphenicol, aminopyrine.

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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