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6.7 Rheumatoid Factor (RF)
The rheumatoid factor test measures the amount of the rheumatoid factor in the blood sample. The rheumatoid factor(RF) is an autoantibody that destroys the patient’s own tissues resulting in stiffness, joint pain, and inflam- mation. The rheumatoid factor test is used to differentiate rheumatoid arthritis from other forms of arthritis.
There are two types of rheumatoid factor tests: (1) the agglutination test and (2) the nephelometry test. The rheumatoid factor is one of the other signs and symptoms 1used to diagnose rheumatoid arthritis. A patient may have a high level of rheumatoid factor but no symptoms of rheumatoid arthritis. However, the patient is likely
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to develop rheumatoid arthritis in the future. A patient may have a normal level of rheumatoid factor and symp- toms of rheumatoid arthritis will likely require a second rheumatoid factor test.
Why the Test Is Performed
The test screens for rheumatoid arthritis.Before Administering the Test
Assess the patient’s age. Patients older than 65 years of age normally have a higher rheumatoid factor level.
How the Test Is Performed
A sample of blood is taken from the patient’s vein. The patient will experience a tight feeling when the tourni- quet is tightened, a pinch or nothing at all when the needle is inserted into the vein, and pressure when a gauze pad is pressed against the insertion site to stop bleeding. It can take up to 10 minutes for bleeding to stop if the patient is taking anticoagulants (aspirin, coumadin). A small bruise might appear at the insertion site, which could become swollen following this test. This is called phlebitis. Applying a warm compress several times a day will reduce the swelling.
Teach the Patient
Explain why the sample is taken and that the healthcare provider may ask for a second rheumatoid factor test if the first test is normal and the patient shows signs of rheumatoid arthritis.
Understanding the Test Results
The rheumatoid factor test results are available quickly. Results are reported as a titer. A titer specifies how much of the sample of blood is diluted with saline before antibodies are no longer detected. The titer is reported as a ratio of parts of the blood sample and saline. The higher the second number of the ratio, the greater num- ber of antibodies in the blood sample.
• Normal test results: 1:20 to 1:40 or less
Higher levels may indicate: Rheumatoid arthritis, systemic lupus erythematosus (SLE), vasculitis, scleroderma, cirrhosis, hepatitis, leukemia, endocarditis, mononucleosis, malaria, tuberculosis, and syphilis.
Solved Problems
Immunoglobulins
6.1 What are immunoglobulins?
Immunoglobulins are antibodies made by the immune system in response to a microorganism that enter the body, an allergen, and abnormal cells such as cancer cells.
6.2 What are the five major types of immunoglobulins?
IgA, IgG, IgM, IgE, and IgD.
6.3 What is IgE?
IgE is found on mucous membranes, lungs, and skin and defends against allergens. A high level of IgE immunoglobulins is common in patients who are hyperallergenic. This type makes up less than 5% of immunoglobulins.
6.4 What is IgA?
IgA is found in tears and saliva and protects the ears, eyes, breathing passages, digestive tract, and vagina exposed to outside antigens. This type makes up 10% of immunoglobulins.
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6.5 What is IgM?
IgM is found in blood and lymph fluid and is the first response to infection. This type makes up 5% of immunoglobulins and forms when an infection occurs for the first time.
6.6 Why is the Immunoglobulin test ordered?
The Immunoglobulin test assesses the levels of immunoglobulins to determine the strengths of the patient’s immune system, the patient’s immunization, and the effectiveness of treatment for infection and bone marrow cancer. The test screens for allergies, autoimmune diseases, multiple myeloma, and macroglobulinemia cancers.
6.7 What might cause a high value of IgA?
A high value of IgA can be caused by systemic lupus erythematosus (SLE), rheumatoid arthritis, multiple myeloma, cirrhosis, and chronic hepatitis.
6.8 What might a high value of IgE indicate?
A high value of IgE might indicate asthma, allergic reaction, parasite infection, atopic dermatitis, or multiple myeloma.
6.9 What might a lower value of IgG indicate?
A lower value of IgG might indicate leukemia, nephrotic syndrome, and macroglobulinemia.
Antinuclear Antibody
6.10 Why is the antinuclear antibody test ordered?
The test screens for rheumatoid arthritis, systemic lupus erythematosus (SLE), polymyositis, and scleroderma.
6.11 How could medication for high blood pressure affect the antinuclear antibody test?
Medication for high blood pressure, heart disease, and tuberculosis (TB) can cause the results to be high.
6.12 What is diagnosed by the results of the antinuclear antibody test?
The test result is a sign and not a definitive diagnosis. Additional assessment must be made before a diagnosis is reached.
6.13 How is the result of the antinuclear antibody test reported?
Results are reported as a titer.
6.14 What is a titer?
A titer specifies how much of the sample of blood is diluted with saline before antibodies are no longer detected. The titer is reported as a ratio of parts of the blood sample and saline. The higher the second number of the ratio, the greater the number of antibodies in the blood sample.
6.15 What might a high result of the antinuclear antibody test indicate?
A high result of the antinuclear antibody test might indicate rheumatoid arthritis, systemic lupus erythematosus (SLE), scleroderma, polymyositis, Raynaud’s syndrome, Addison’s disease, Hashimoto’s thyroiditis, hemolytic anemia, vitamin B12deficiency, hepatitis, or idiopathic thrombocytopenia.
6.16 Other than medication, what might cause a false elevated result of the antinuclear antibody test?
Older adults also show an elevated result due to aging. A patient who has a family history of autoimmune disease may have an elevated result.
Human Immunodeficiency Virus (HIV) Tests
6.17 Name two HIV tests.HIV-1 is common in nearly all acquired immunodeficiency syndrome (AIDS) cases.
HIV-2 is associated with West Africa. HIV causes AIDS, which is incurable.
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6.18 What does HIV infect?
The human immunodeficiency virus (HIV) infects the CD4⫹white blood cells that are the body’s defense against infection.
6.19 What is the seroconversion period?
There is a period when the HIV infection is not detectable in a patient. This is called the
seroconversion period, also known as the window period. The patient can spread HIV during this period.
6.20 How long is the seroconversion period?
The seroconversion period can be as short as 2 weeks and as long as 6 months.
6.21 When should the HIV test be administered?
After the seroconversion period, the human immunodeficiency virus test is able to detect HIV antibodies or the HIV’s RNA in the patient’s blood. Testing is performed when the patient exhibits symptoms of HIV, has HIV risk factors, is donating blood or organs, or is pregnant. An infected mother can be treated, decreasing the likelihood that HIV will be passed to the fetus.
6.22 What are the HIV tests?
The HIV tests are enzyme-linked immunosorbent assay (ELISA), Western blot, polymerase chain reaction (PCR), indirect fluorescent antibody (IFA), saliva test, rapid test kits, and home blood test kits.
6.23 What is the enzyme-linked immunosorbent assay test?
The first test administered to screen a patient. This looks for HIV antibodies in the blood.
6.24 What would you expect if the enzyme-linked immunosorbent assay test is positive?
If the test result is positive, another ELISA test is performed. Other tests are performed if there are two positive ELISA tests, because the ELISA test can produce a false positive.
6.25 Why is the polymerase chain reaction administered?
This looks for HIV’s RNA in the blood. PCR is used to identify a very recent infection and is administered to screen blood and organs before donations and when HIV antibody tests are inconclusive. The PCR test is not performed often, due to expense.
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