About your Lab Tests
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ESR and CRP
Both are nonspecific markers for inflammation. Anything that causes inflammation can cause these to be elevated (autoimmune diseases, infection, cancer, heart disease, etc) Elevation of these tests may be associated with active autoimmune disease. ESR can also be elevated in many other conditions, such as obesity and anemia.
A high uric acid can lead to gout. However, a high uric acid is not the same as gout. About 1/5 Americans has a high uric acid. Of these, only about 1/5 will actually get gout.
A high uric acid is defined as a uric acid over 6mg/dl. Typically, a patient with gout has a high uric acid. However, a normal uric acid (below 6mg/dl) does not rule out gout. A patient can still get gout attacks with a normal uric acid level.
Furthermore, even in patients who have a high uric acid at baseline, the uric acid level can be below 6mg/dl during an acute attack in up to 50% of patients.
Patients with gout should follow a gout prudent diet. Foods to avoid or minimize include:
Alcohol, but especially beer.
Red meats (including pork)
Shellfish and certain other fish (salmon, mackerel, anchovies, trout, tuna, cod, herring, sardines)
Foods high in fructose. High fructose corn syrup is a very commonly used sweetener. Certain fruits are naturally high in fructose as well (apples, oranges, raisins).
ANA (Anti-Nuclear antibody)
Nonspecific antibody that is associated with many autoimmune diseases. Classically a positive ANA is associated with Lupus.
However, most patients with a positive ANA do not have Lupus. Rather, it is often an incidental finding, or it may be associated with some other autoimmune disease. Many “non-rheumatologic” diseases, such as thyroid disease and Crohn’s/Ulcerative colitis are often associated with positive ANAs.
A positive ANA is much easier to understand through an analogy. Antibodies are part of the body’s defense system. They are proteins that help to prevent and cure infections. The production of antibodies is the reason that children (and adults) are vaccinated.
Antibodies can be seen as the body’s soldiers. Just as some actual soldiers can become traitors, some antibodies can become “traitors” as well. These antibodies are no longer interested in fighting diseases or foreign invaders, but rather are more interested in fighting you. This is what an ANA is. It is an antibody that is directed against part of your cells, the center of the cells, or Nucleus, to be exact.
However, just because a soldier decides he/she no longer likes the USA, does not mean that he/she is actually going to do anything about it. And just because you have an ANA, does not mean that your body is being attacked. In fact most ANAs do not actually do anything. In one study, low level ANAs (titers of 1:40) occurred in 32% of normal patients, moderate level ANAs (titers of 1:80) occurred in 13% of normal patients, and high level ANAs (titers of 1:320) occurred in 3% of normal patients. Up to 37% of those over 65 can have a positive ANA.
This is why it is difficult to interpret ANAs. Many factors need to be considered and evaluated, such as clinical symptoms and the results of other laboratory tests. This is what Rheumatologists do.
ENA (SSA(Ro), SSB(La), RNP, smith, Jo-1, SCL70, Centromere, Histone)
ENA stands for extractable nuclear antibody. The various ENAs are different types of ANAs. Each ENA is often associated with specific diseases. Common/typical associations are as follows:
SSA- Sjogrens, lupus, ,rheumatoid arthritis
SSB- Sjogrens, lupus, rheumatoid arthritis
RNP- Mixed connective tissue disease (combination of rheumatoid arthritis, lupus, scleroderma, and/or myositis).
SCL70- Systemic Sclerosis or Scleroderma
Centromere- Limited cutaneous scleroderma (CREST)
Histone- Drug induced lupus
DS DNA (double stranded DNA)
Antibody that is usually associated w/ lupus.
These are proteins that are often low in certain autoimmune diseases, such a lupus. They can sometimes be used to measure disease activity in SLE patients. Low levels may suggest active disease. They can also be low in other “complement fixing” diseases. Elevated complements are not of clinical concern and often occur in acute inflammatory states (infection, autoimmune diseases, etc).
Antibodies that may be associated with an increased risk of thrombosis (Blood clot or DVT, stroke, heart attack) or pregnancy complication (miscarriage, preterm berth, preeclampsia/eclampsia). High titers are more likely clinically significant. IgG antibodies are more likely to be associated with clinical events than IgM. IgA are the least clinically significant. Often associated with Lupus.
Anti-Beta 2 Glycoprotein 1 IgG and IgM
These are a type of anti-cardiolipin and may be more strongly associated with events than anti-cardiolipins. Often associated with lupus.
If present, patient also has increased risk for thrombosis and pregnancy complication. Often associated with lupus.
CCP—Anti-Cyclic Citrullinated peptide
Also a marker for RA. This is more specific than RF. In other words, a positive CCP (especially in high titer) is most often associated with Rheumatoid Arthritis. When both RF and CCP are positive, there is a very high likelihood of RA.
SPEP-Serum Protein Electrophoresis
MGUS (Monoclonal gammopathy of unknown significance) occurs in over 3% of the general population over the age of 50 and is typically detected as an incidental finding when patients undergo a protein electrophoresis as part of an evaluation for a wide variety of clinical symptoms and disorders (eg, peripheral neuropathy, vasculitis, hemolytic anemia, skin rashes, hypercalcemia, or elevated sedimentation rate). The prevalence of MGUS in persons ≥50, ≥70, and ≥85 years of age was 3.2, 5.3, and 7.5 percent, respectively. If positive, a urine immunoelectrophoresis and serum immunoelectrophoresis are obtained. If either is abnormal, referral to hematology is indicated.
Myositis specific antibody panel
This is a panel of antibodies that can be associated with autoimmune myositis (dermatomyositis, polymyositis). This is a very specialized test only run by a few labs in the country and takes up to 3 weeks to obtain results.
ANCA—Anti-Neutrophil Cytoplasmic Antibody
This is an antibody test that can be associated with many autoimmune diseases, especially vasculitis. A “C-ANCA” is fairly specific for Wegener’s Granulomatosis, a vasculitis that usually effects the sinuses, lungs, kidneys, and skin. When a C-ANCA is positive, it is confirmed by ordering a PR-3. If PR-3 is positive, Wegener’s is very likely. A P-ANCA is not as specific as a C-ANCA and can be associated with many autoimmune diseases, vasculitides, bowel disease etc. A P-ANCA should be followed by a test for MPO. If MPO is positive, Microscopic polyangitis (a vasculitis) is likely.
These are markers for myositis. If elevated, a myositis (inflammation of muscle) needs to be ruled out. Auto-immune Myositis includes dermatomyositis, polymyositis, and inclusion body myositis.
Gluten sensitivity panel
This checks for antibodies that are often associated with celiac sprue. IgA Anti-endomesial antibodies and IgA Tissue transglutaminase antibodies have the highest diagnostic accuracy. Even low titers of anti-endomesial antibodies are specific for celiac sprue. Anti TTG is very sensitive and specific. This disease is often occult. It can cause GI complaints. It is also a cause of isolated transaminitis. Patients with celiac sprue may present to a rheumatologist with pain as their major complaint. A gluten free diet will ultimately “cure” them.
25-Hydroxylated vitamin D
Should be over 30. Low vitamin D is associated with osteoporosis and fractures. However, a low vitamin D has also been associated with many symptoms including fatigue, pain, memory issues, etc. In many patients, sun exposure is NOT ENOUGH to raise vitamin D to an acceptable level.
High in patients with renal failure or vitamin D deficiency (secondary hyperparathyroidism). However, if D is normal and creatinine is normal, consider Primary Hyperparathyroidism (especially if calcium and alkaline phosphatase are elevated). Primary hyperparathyroidism is often an occult disease that can lead to osteoporosis.
ACE or Angiotensin Converting Enzyme
Angiotensin Converting Enzyme is an enzyme that is often elevated in patients with sarcoidosis. However, this test is not very sensitive or specific. Sarcoidosis is a disease that primarily effects the lungs. However, any organ system can be involved, including the musculoskeletal system, skin, eyes, heart, and others.
Classically a marker for rheumatoid arthritis (RA). 80% of patients with longstanding RA have this test positive, usually high titer. In early RA, less patients have this test positive. This test can also be positive in many other diseases, such as hepatitis C and endocarditits. It can be elevated in up to 10% of the normal population, usually at a low titer.
This is an allele (gene) that patients are born with. 5-10% of patients with this gene have ankylosing spondylitis. But, 90-95% of patients with ankylosing spondylitis have this gene. Ankylosing spondylitis is an autoimmune disease associated with back pain, joint pain and swelling, and often eye problems (uveitis/iritis).
Proteins that are present in some forms of vasculitis. Can be associated with hepatitis C and myeloma.
Antibodies that can be present in Crohn’s disease. If positive, patient probably needs to see GI for a colonoscopy.
If antibody test is positive, a western blot is performed. In order for this test to be positive, a patient must have 5 IgG bands or 2 IgM bands. Some bands (like p41) are very common.