Sorted By Test Name - Mayo Medical Laboratories

DDI
9290
Useful For: Antineutrophil cytoplasmic antibodies (cANCA and pANCA): -Evaluating patients
suspected of having autoimmune vasculitis (both Wegener granulomatosis [WG] and microscopic
polyangiitis) cANCA titer: -May be useful for monitoring treatment response in patients with WG
(systemic or organ-limited disease); increasing titer suggests relapse of disease, while a decreasing titer
suggests successful treatment When used for diagnosis it is recommended that specific tests for proteinase
3 (PR3) ANCA and myeloperoxidase (MPO) ANCA be performed in addition to testing for cANCA and
pANCA.(2) This panel of tests is available by ordering the VASC/83012 Antineutrophil Cytoplasmic
Antibodies Vasculitis Panel, Serum.
Interpretation: Positive results for antineutrophil cytoplasmic antibodies (cANCA or pANCA) are
consistent with the diagnosis of Wegener granulomatosis (WG), either systemic WG with respiratory and
renal involvement or limited WG with more restricted end-organ involvement. Positive results for
pANCA are consistent with the diagnosis of autoimmune vasculitis including microscopic polyangiitis
(MPA) or pauci-immune necrotizing glomerulonephritis. Sequential measurements of titers of cANCA
may be useful to indicate the clinical course of patients with WG. Changes in titer of > or =2 serial
dilutions are considered significant.(3) In patients with very low levels of cANCA, the immunofluorescent
staining pattern may mimic the pANCA pattern. In patients with MPA, monitoring of disease activity may
be performed by measuring MPO ANCA (MPO/80389 Myeloperoxidase Antibodies, IgG, Serum).
Reference Values:
Negative
If positive for cANCA, results are titered.
Clinical References: 1. Russell KA, Wiegert E, Schroeder DR, et al: Detection of anti-neutrophil
cytoplasmic antibodies under actual clinical testing conditions. Clin Immunol 2002:103;196-203 2.
Savige J, Gillis D, Benson E, et al: International consensus statement on testing and reporting of
antineutrophil cytoplasmic antibodies (ANCA). Am J Clin Pathol 1999:111;507-513 3. Specks U,
Homburger HA, DeRemee RA: Implications of cANCA testing for the classification of Wegenerâ€s
Granulomatosis: performance of different detection systems. Adv Exp Med Biol 1993:336;65-70
D-Dimer, Plasma
Clinical Information: Thrombin, the terminal enzyme of the plasma procoagulant cascade, cleaves
fibrinopeptides A and B from fibrinogen, generating fibrin monomer. Fibrin monomer contains D
domains on each end of the molecule and a central E domain. Most of the fibrin monomers polymerize to
form insoluble fibrin, or the fibrin clot, by repetitive end-to-end alignment of the D domains of 2 adjacent
molecules in lateral contact with the E domain of a third molecule. The fibrin clot is subsequently
stabilized by thrombin-activated factor XIII, which covalently cross-links fibrin monomers by
transamidation, including dimerization of the D domains of adjacently polymerized fibrin monomers. The
fibrin clot promotes activation of fibrinolysis by catalyzing the activation of plasminogen (by
plasminogen activators) to form plasmin enzyme. Plasmin proteolytically degrades cross-linked fibrin,
ultimately producing soluble fibrin degradation products of various sizes that include cross-linked
fragments containing neoantigenic D-dimer (DD) epitopes. Plasmin also degrades fibrinogen to form
fragments X, Y, D, and E. D-dimer immunoassays use monoclonal antibodies to DD neoantigen and
mainly detect cross-linked fibrin degradation products, whereas the fibrino(geno)lytic degradation
products X, Y, D, and E and their polymers may be derived from fibrinogen or fibrin. Therefore, the
blood content of D-dimer indirectly reflects the generation of thrombin and plasmin, roughly indicating
the turnover or activation state of the coupled blood procoagulant and fibrinolytic mechanisms.
Useful For: Diagnosis of intravascular coagulation and fibrinolysis, also known as disseminated
intravascular coagulation, especially when combined with clinical information and other laboratory test
data (eg, platelet count, assays of clottable fibrinogen and soluble fibrin monomer complex, and clotting
time assays-prothrombin time and activated partial thromboplastin time).(2) Excluding the diagnosis of
acute pulmonary embolism or deep vein thrombosis, particularly when results of a sensitive D-dimer
assay are combined with clinical information, including pretest disease probability.(3-6)
Interpretation: D-dimer values < or =250 ng/mL D-dimer units (DDU) (< or =0.50 mcg/mL
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