Understanding and evaluating common laboratory tests pdf

Basic Microbiology Tests. Tests for Disorders of Immune Function. Pearson offers affordable and accessible purchase options to meet the needs of your students. Connect with us to learn more. We're sorry! We don't recognize your username or password. Please try again. The work is protected by local and international copyright laws and is provided solely for the use of instructors in teaching their courses and assessing student learning.

You have successfully signed out and will be required to sign back in should you need to download more resources. Out of print. Understanding and Evaluating Common Laboratory Tests. If You're an Educator Additional order info. Overview Features Contents Order Overview. Description For nursing courses in lab and diagnostic testing, and non-nursing courses in testing, including those for PAs, lab technicians, and other health related professions.

Clear, logical writing style. Enhances comprehension of material. Highlights important chapter concepts for the student. Table of Contents 1. Sign In We're sorry! Username Password Forgot your username or password? Protein vaccinations, like tetanus toxoid, measure T-cell dependent responses.

Polysaccharide vaccines, like Pneumovax, measure T-cell independent responses. Testing of specific antibody titers such as to influenza immunization are reported relative to protective values. These values are based on epidemiologic data regarding protection in larger populations. For randomly acquired antibody levels, an initial comparison to protective values can be used to decide if a proper immune response was achieved.

A four-fold increase in titers to protein vaccination indicates a normal response. A two-fold increase in titers to a polysaccharide antigen indicates a normal response.

Failure to mount an appropriate response to antigen is a clue to the physician to pursue B and T cell function further. Cryoglobulins are immunoglobulins that precipitate reversibly in cold temperatures. In disease states, these antibodies can bind with complement proteins and other peptides to form immune complexes and cause tissue damage.

Three types of cryoglobulins exist. Type I cryoglobulins are monoclonal immunoglobulins often of the IgM isotype. At phlebotomy, whole blood is obtained in pre-warmed tubes without anti-coagulant and maintained at body temperature until coagulation occurs about one hour. The sample is then centrifuged and the clot is removed.

The specimen is then examined daily to determine if proteins have precipitated. Once a precipitate is present, the sample is spun again and a cryocrit is measured in a calibrated tube. Cryoglobulins are nonspecific indicators of disease states. Type I monoclonal cryoglobulins are associated with multiple myeloma, Waldenstrom's macroglobulinemia, and lymphoproliferative disorders. Cryoglobulins are rarely found in children. In autoimmune disease, serum antibodies that inhibit or prolong in vitro clinical laboratory coagulation tests are termed anti-phospholipid antibodies aPL, also called anti-cardiolipin antibodies or lupus anticoagulant because they are directed against phospholipids and phospholipid-binding proteins.

The existence of these antibodies is associated with the anti-phospholipid antibody syndrome APS. APS can occur independent or with systemic rheumatic diseases.

Anti-phospholipid antibodies can also be found in healthy individuals and in patients with various infections that do not have features of anti-phospholipid antibody syndrome. The term anticoagulant is paradoxical in that the presence of aPL are associated with thromboses in patients.

The presence of aPL can be directly measured by enzyme linked assays. Beta-2 glycoprotein I has been identified as one of the major antigenic determinants of antiphospholipid antibodies.

Initial applications of flow cytometry pertained to the interest in certain cell populations, for example the numbers of lymphocytes in patients infected with human immunodeficiency virus HIV. However, the methodology has greatly expanded its role such that cell cycle analysis, quantification of malignant cells and activation status of lymphocyte subpopulations can be determined.

When evaluating a patient with a suspected immunodeficiency, flow cytometry is crucial to determine the quantitative number of immune cells typically T, B and NK natural killer cells. Remember, flow cytometry testing reveals numbers of cells and does not indicate cellular function.

Testing for cellular functioning involves other laboratory methods, such as quantitative immunoglobulin levels to indicate proper B cell function. The markers commonly used to assess lymphocyte subsets by flow cytometry are as listed in Table 4. The flow cytometry device consists of an illumination source, an optical bench, fluidic system, electronic monitoring and computer.

Cells that will flow through the cytometer are first prepared by tagging cell surface molecules with fluorescently labeled monoclonal antibodies. Illumination of the cell occurs by air-cooled lasers that provide a monochromatic light source argon at nm or blue, helium neon at nm or red. The point of illumination occurs within the flow cell.

The optical bench contains lenses that shape and focus the illumination beam. Nonfluorescent and fluorescent signals generated by the labeled cell are collected and measured by a detection system consisting of filters linked to a photodetector.

Cells are injected into a moving fluid sheath to establish a focused single-file flow of cells that move through the analysis point. Differences in the magnitude of emission signal generated from each cell reflect biologic differences between the cells. Software collects data that analyzes cell subpopulations based on the presence or absence of labeled antibody binding. Data is then presented as fluorescence intensity versus cell number. Cytokines are molecules secreted by a variety of cells that function in cellular communication.

Immunologists are keenly interested in cytokines, particularly those that influence immune function and inflammation.

Commercial testing laboratories do not routinely assay most serum cytokine levels, as this testing is largely done in research laboratories. Testing is laborious because of the labile nature of these small molecules.

After phlebotomy, the serum needs to be quickly removed from the cellular components and frozen as quickly as possible and testing should not be delayed. There is extensive evidence that these cytokines promote inflammation and therefore have become targets for therapy.

Rheumatoid arthritis is the best example of an autoimmune illness where anti-TNF therapy has revolutionized the natural history of the disease.

Targeting TNF with proteins fusion produced or monoclonal antibodies that antagonize TNF action results in dramatic improvement of disease activity.

In fact, rheumatoid arthritis is the prototypic autoimmune disease where the efficacy of anti-cytokine therapy is best demonstrated. MHC class I and II genes are the major genetic determinants of susceptibility to many autoimmune diseases.

Detection of HLA type can be done routinely and can be assayed using several methods that include gel electrophoresis, polymerase chair reaction PCR , ELISA, and newer methods employing high-throughput detection of nucleic acid.

Sarcoidosis is a systemic granulomatous disease characterized by noncaseating granulomas affecting multiple organ systems. The etiology of sarcoidosis is not known but believed to involve chronic inflammation, with a Th-1 cellular contribution, and because immunosuppressive therapy is beneficial. Biopsy of the affected tissue is vital to diagnosis and histological findings should show noncaseating granulomas.

Imaging studies, in particular, chest x-ray or chest CT, show bilateral hilar lymphadenopathy and or interstitial infiltrates. Chest CT reveals nodular infiltrates that tend to be distributed along the bronchoalveolar structures. Laboratory investigations helpful in the diagnosis of sarcoidosis include a serum angiotensin converting enzyme ACE level and vitamin D levels.

ACE levels are generally elevated, however, ACE levels lack disease specificity and therefore have limited diagnostic and therapeutic utility. Churg-Strauss syndrome CSS is a necrotizing vasculitis affecting small and medium blood vessels characterized by eosinophilic infiltration, eosinophilic granulomas, nasal polyps, allergic rhinitis, conductive hearing loss, eye disease scleritis, episcleritis, uveitis , asthma, fleeting infiltrates, alveolar hemorrhage, segmental necrotizing glomerulonephritis, heart failure, and vasculitic neuropathy.

Initial symptoms typically suggest a reactive airway process similar to asthma. As is the case with any suspected vasculitis, a biopsy of the involved organ showing an inflammatory destruction of the blood vessels, with eosinophilic infiltrates and granuloma formation is vital for diagnosis. WG is characterized by systemic granulomatous vasculitic lesions of the upper and lower respiratory tract and the kidney. MPA is characterized by nongranulomatous vasculitic lesions of the lower respiratory tract, kidney, skin and nerve.

Both of these diseases can be manifested by acute renal failure with the urinalysis showing RBCs, RBC casts, and proteinuria. Renal biopsy reveals a segmental necrotizing glomerulonephritis with a characteristic lack of immune complexes. WG can be a chronic, undiagnosed illness where a patient complains of chronic sinusitis that may cause nasal septal perforation. The auditory nerve can be inflamed causing a conductive or sensorineural hearing loss. Pathognomonic to Goodpasture's syndrome are autoantibodies to the renal glomerular and lung alveolar basement membrane.

The specific autoantigen is the amino acid carboxy-terminal noncollagenous domain of type IV collagen. Diagnostic testing includes the detection of antiglomerular basement membrane antibodies. In cases where only the presence of diffuse alveolar hemorrhage occurs, antibodies may not be present. In those cases, the diagnosis is established by demonstrating linear immunofluorescence in lung tissue.

Many autoimmune diseases have pulmonary complications. Pleural effusions and pleurisy can be bilateral in up to one-forth of cases of RA. Pleurisy is very common in SLE. Other pulmonary diseases in SLE include pneumonitis, pulmonary hemorrhage, and shrinking lung syndrome.

These pulmonary processes may cause cough with hemoptysis, and dyspnea. The antiphospholipid syndrome's pulmonary manifestations consist of pulmonary thromboembolism and pulmonary hypertension. Scleroderma pulmonary manifestations of interstitial lung disease and pulmonary hypertension are the leading cause of death in systemic sclerosis. The astute physician will be aware of the patient's symptoms so that they can pursue further investigations into the etiology of pulmonary disease.

Remembering that chronic lung disease can be associated with spurious rheumatoid factor autoantibodies, one must test for serum autoantibodies that are specific to a disease state. Anti-CCP antibodies help to diagnose rheumatoid arthritis if accompanied by radiographic evidence demonstrating erosive disease and clinical evidence of joint involvement. The presence of anti-phospholipid antibodies can be confirmed with a positive lupus anticoagulant test, or anti-cardiolipin antibody or beta-2 glycoprotein antibody.

The diagnosis of scleroderma is assisted with anti-SCL antibodies or anti-centromere antibodies. For suspected lung disease associated with a myopathy, elevations of CK, AST, ALT, aldolase in conjunction with the presence of a myositis-specific autoantibody are very helpful. Amyloidosis describes a group of disorders characterized by the extracellular tissue deposition of a variety of low molecular weight proteins called amyloid.

Currently, there are more than 25 types of amyloid. The most frequent is type AL, which is found in primary amyloidosis as well as in myeloma-associated amyloidosis. Type AA, is found in secondary amyloidosis, associated with chronic infections or inflammatory disease and some periodic fever syndromes, such as Familial Mediterranean fever.

Deposition of AL and AA, occurs primarily in the kidneys causing asymptomatic proteinuria, nephrotic syndrome, renal failure, and ESRD , heart cardiomyopathy, systolic or diastolic dysfunction, heart block, angina or infarct and liver hepatomegaly and gastrointestinal gastroparesis, constipation, bacterial overgrowth, malabsorption and intestinal pseudo-obstruction. Amyloidosis from chronic inflammation will reveal an elevated ESR and CRP — clues to suggest inflammation is present and amyloid should be considered as a cause of organ dysfunction.

Testing serum levels of type A amyloid is possible in research laboratories. Diagnosis is confirmed by tissue or aspiration biopsy of the affected organ looking for birefringent material on Congo red stain. Henoch-Schonlein purpura is an immune-mediated vasculitis associated with immunoglobulin A IgA deposition and is the most common form of systemic vasculitis in children.

Signs and symptoms include palpable purpura, arthritis, arthralgias, abdominal pain and renal disease. Adults with HSP have presentations similar to children and are at increased risk for developing significant renal disease.

Renal disease presents similarly to IgA nephropathy - characterized by deposition of IgA immune complexes causing glomerulonephritis. Renal biopsy discloses IgA deposition in the mesangium. Systemic lupus erythematosus is an autoimmune disease that can affect most organs.

In active disease, both the classic and alternative complement cascades are activated resulting in depressed serum levels of complement components C3 and C4 are typically tested.

Most patients with lupus nephritis will have high titers of anti-dsDNA auto-antibodies. As described previously in the immunologic lung disease section of this chapter, antiglomerular basement membrane disease or Goodpasture's syndrome is characterized by anti-GBM autoantibodies. Patients presenting with renal involvement often have abrupt onset of oliguria or anuria, hematuria, and anemia. Immunofluorescence IF demonstrates linear deposition of IgG along the glomerular capillaries and occasionally the distal tubules.

Rarely, IgA or IgM may be present. As discussed previously, this small to medium sized vasculitis is able to cause inflammation in several tissues. Vasculitis often involves the kidney causing proteinuria, hematuria, cellular casts, hypoalbuminemia and renal failure. In a similar fashion discussed previously where autoimmune diseases cause pulmonary disease, the same scenario is seen with autoimmune disease and renal involvement. Proteinuria may be the first clue that the kidney is involved from the result of chronic inflammation or immune complex deposition.

Persistent inflammation seen in rheumatoid arthritis can cause a membranous nephropathy, the result of reactive amyloid deposition. One must also remember that therapies to treat inflammatory disease, as seen in RA, such as medications like gold or penicillamine can cause proteinuria.

Vasculitis lesions may also occur in patients with severe RA. Therefore, a vigilant watch of renal function with frequent urinalysis is critically important in monitoring the autoimmune patient. Polymyositis, dermatomyositis, and inclusion body myositis constitute the idiopathic inflammatory myopathies IIM. While the etiology is not well defined, muscles become inflamed as the result of both humoral and cellular immune dysfunction causing a lymphocytic infiltration and muscle damage.

These myopathies differ in their etiology, clinical presentation, and histology. Polymyositis is defined by symmetric proximal muscle weakness, elevations in muscle enzymes, characteristic EMG findings and a muscle biopsy that shows inflammation.

The illness is progressive with clinical symptoms that may include myalgias, dysphagia, and dyspnea. Dermatomyositis mimics polymyositis with the addition of skin rashes such as a heliotrope rash and Gottron's papules. The rate of malignancy is increased in patients with IIM, more so in DM patients and may precede, coincide with or postdate the diagnosis. Therefore, screening for malignancy is very important.

Inclusion body myositis is the most common form of IIM in patients over the age of Features that set IBM apart from other forms of myositis are asymmetry and distal involvement, particularly affecting the foot extensors and finger flexors. The disease tends to be indolent in its progression and resistant to therapy.

Diagnostic testing for myositis includes common laboratory tests CBC, CMP , serologies, imaging studies and muscle biopsy. CK levels usually rise 10 to fold of normal and transaminases can increase to 10 fold.

For example, anti-tRNA synthetase antibodies eg. PM typically demonstrates a lymphocytic infiltration seen mostly within the fascicles endomysial inflammation , some fiber necrosis, degenerative and regenerative fibers. MHC class I antigens on fibers identified by immunohistochemistry can also be seen. In dermatomyositis, perifascicular atrophy is common. Large, atrophic or angulated fibers are also present. Two major types of AIHA exist — warm and cold.

The etiology of warm AIHA includes infections often in children , autoimmune diseases SLE , malignancies of the immune system Non-Hodgkin's lymphoma, chronic lymphocytic leukemia , prior allogenic blood transfusion, and certain drugs cephalosporins, hydralazine, isoniazid INH , sulfonamides, tetracycline, triamterene.

Signs and symptoms of mild warm AIHA include anemia, occasionally jaundice, and mild to moderate splenomegaly with severe cases also involving fever, tachypnea, tachycardia, angina or heart failure. Peripheral blood exam cam show leukopenia, neutropenia or thrombocytopenia but often patients have a normal platelet count, neutrophilia, and mild leukocytosis.

Peripheral blood smear reveals polychromasia, spherocytosis, fragmented and nucleated erythrocytes and sometimes erythrophagocytosis by monocytes in severe cases. Reticulocytosis is commonly present.

Serum haptoglobin levels are decreased and LDH increased. The majority of cold-reactive autoantibodies are cold agglutinins. CAS usually occurs in middle-aged and elderly persons with IgM the responsible immunoglobulin. Signs and symptoms are chronic anemia, dark urine, acrocyanosis, pallor and jaundice. Laboratory testing includes mild to moderate anemia with prominent autoagglutination, abnormal erythrocyte morphology, reticulocytosis, jaundice, hemoglobinuria, and erythroid hyperplasia in the bone marrow.

PCH frequently occurs in children, often after an upper respiratory infection and IgG is typically the causative immunoglobulin. Acute attacks are often severe but the illness usually resolves spontaneously within a few days to several weeks.

Signs and symptoms consist of fever, malaise, abdominal pain, dark colored urine, jaundice and pallor. Laboratory findings show anemia often severe , reticulocytosis, abnormal RBC morphology, hemoglobinuria, usually erythroid hyperplasia, leukocytosis and a platelet count that is normal or slightly elevated.

Antiphospholipid syndrome is a thrombophilic disease defined by two major components — the presence of at least one type of autoantibody antiphospholipid antibody aPL as mentioned earlier in this chapter , which are directed against phospholipid-binding plasma proteins, and the occurrence of at least one of several clinical features recurrent fetal loss, arterial thromboses, or thrombocytopenia.

Primary antiphospholipid antibody syndrome is diagnosed in the absence of other underlying diseases and secondary if another illness such as SLE is identified. Therapy consists of anticoagulation and treating any coexisting illness that may give rise to antiphospholipid antibodies.

Immune or idiopathic thrombocytopenic purpura ITP is an acquired disorder without a clear etiology. Both acute and chronic forms occur.

The pathogenesis is thought to occur through a combination of increased platelet destruction and inhibition of megakaryocyte platelet production by specific IgG autoantibodies. Clinical manifestations are variable, can be abrupt or acute, and often are insidious. Symptoms include bleeding ranging from petechiae and easy bruising to severe bleeding diathesis. Intracranial hemorrhage is quite rare. Children often exhibit symptoms after a viral or bacterial infection. Thrombocytopenia is noted on lab work.

Bone marrow cellularity is normal with normal erythropoiesis and myelopoiesis. Megakaryocytes are present in normal to increased numbers. However, bone marrow examination is not usually required unless another disease is suspected or if the patient is greater than 60 years of age because of concern for myelodysplasia. Post-transfusion purpura PTP is a rare condition that usually develops seven to ten days after a red blood cell transfusion.

The syndrome is characterized by severe thrombocytopenia and bleeding caused by alloimmunization to human platelet specific antigens following a blood component transfusion. Patients are usually middle-aged multiparous females, although PTP has also been reported in males. Most cases occur with the formation of human platelet antigen — 1a antibodies. Clinical Immunology Principles and Practice, Third edition. Chapter 97, page , Figure Reprinted with permission. Chapter 97, page , figure Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication.

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Author information Copyright and License information Disclaimer. Contact Information: Christine Castro, D. Copyright notice. The publisher's final edited version of this article is available at J Allergy Clin Immunol. See other articles in PMC that cite the published article. Abstract Laboratory testing is of great value when evaluating a patient with a suspected autoimmune disease.

Keywords: autoimmune, disease, laboratory, inflammatory markers, evaluation, rheumatic, serologies, flow cytometry, HLA, organ-specific. Introduction Autoimmunity involves the loss of normal immune homeostasis such that the organism produces an abnormal response to its own self tissue.

Initial laboratory evaluation Inflammatory diseases will cause abnormalities in routine laboratory studies. Inflammatory markers Serum proteins that are produced in response to inflammation can be referred to as inflammatory markers.

Ferritin Serum ferritin is a storage protein for iron and its synthesis is regulated by intracellular iron, cytokines TNF-alpha, IL-1, and IL-6 , products of oxidative stress, and growth factors. Ceruloplasmin the major copper containing protein in the blood that plays a role in iron metabolism and is increased in acute and chronic inflammatory states, pregnancy, lymphoma, rheumatoid arthritis and Alzheimer's disease.

Fibrinogen a hemostatic coagulation factor produced in response to tissue injury. Haptoglobin is produced in response to tissue injury. Albumin a serum protein synthesized by the liver that aids body tissues in maintaining oncotic pressure necessary for proper body fluid distribution. Autoantibodies and Immunologic Studies The presence of an autoantibody in a patient does not assure a diagnosis of an autoimmune disease.

Anti-nuclear antibody ANA Autoantibodies to nuclear antigens are a diverse group of antibodies that react against nuclear, nucleolar, or perinuclear antigens. Open in a separate window. Complement The complement cascade is a complex, tightly regulated series of proteolytic enzymes, regulatory proteins and cell surface receptors that mediate and augment both complement, humoral and cellular immune response.

Immunoglobulins quantitative and qualitative Measuring total quantitative immunoglobulin Ig levels are a key component to any immunologic evaluation. Table 3 Differential diagnosis for immunoglobulin levels. Immunoglobulin Increased Decreased Ig G Infection, inflammation, hyperimmunization, IgG multiple myeloma, liver disease, rheumatic fever, systemic rheumatic disease Agammaglobulinemia, amyloidosis, leukemia, myeloma, preeclampsia IgM Early HIV infection, infectious mononucleosis, lymphoma, macroglobulinemia, myeloma, rheumatoid arthritis Rarely agammaglobulinemai, amyloidosis, leukemia, myeloma IgA Chronic infections especially of gastrointestinal tract , inflammatory bowel disease, myeloma, rheumatic fever Agammaglobulinemia, hereditary IgA deficiency, myeloma or protein-losing enteropathy.

Cryoglobulins Cryoglobulins are immunoglobulins that precipitate reversibly in cold temperatures. Cytokine studies Cytokines are molecules secreted by a variety of cells that function in cellular communication. Specific Immunologic Disease Entities 1. Immunologic Lung Disease Sarcoidosis Sarcoidosis is a systemic granulomatous disease characterized by noncaseating granulomas affecting multiple organ systems.