List of clinical laboratory tests
There are no established biomarkers for myalgic encephalomyelitis or many of its comorbidities. The following are clinically available lab tests used by some practitioners to aid in differential diagnosis or management of patients’ condition.
|Test name||Type||Description||Rationale||Relevant diagnoses||Commercial availability|
|ANA (Antinuclear Antibody)||Serum||Five percent of the apparently "normal population" demonstrate serum ANA. Low titers of ANA reactivity may be seen in patients with rheumatoid arthritis (40% to 60% of patients), scleroderma (60% to 90%), discoid lupus, necrotizing vasculitis, Sjögren's syndrome (80%), chronic active hepatitis, pulmonary interstitial fibrosis, pneumoconiosis, tuberculosis, malignancy, age over 60 (18%), as well as in SLE, especially if the disease is inactive or under treatment. Titers ≥1:160 usually indicate the presence of active SLE, although occasionally other autoimmune disease may induce these high titers. There are now known groups of "ANA-negative" lupus patients. Such patients often have antibodies to SS-A/Ro antigen (usually when a frozen section substrate is used) and subacute cutaneous lupus. Ten percent of patients with SLE manifest biologic false-positive tests for syphilis; this may even be the initial manifestation. Some other tests used in differentiation of autoimmune states include antibody to double-stranded DNA, rheumatoid factor, antibody to extractable nuclear antigens, total hemolytic complement (C3, C4, etc). Although ANA tests are occasionally ordered on cerebrospinal fluid or synovial fluid, the current assays are not standardized for these fluids and such assays do not add to the diagnostic process.||Autoimmune disorders||Labcorp|
|Hydroxyproline||Urine||Hydroxyproline is an amino acid present in appreciable quantities in collagen and excreted in the urine after collagen breakdown. Because urinary hydroxyproline is derived almost entirely from collagen, it reflects the rate of collagen catabolism.||Labcorp, Quest|
|Matrix metalloproteinase-9||Serum||MMP-9 is a marker of inflammation, tissue remodeling, wound healing, and mobilization of tissue-bound growth factors and cytokines. Its expression correlates with abnormal collagen deposition accompanying pancreatic cancer, with lymph node metastasis in breast cancer and with regional vessel invasion by giant cell tumor or bone. MMP-9 contributes to the pathogenesis of numerous clinical disease states, including rheumatic arthritis, coronary artery disease, chronic obstructive pulmonary disease, multiple sclerosis, asthma, and cancer.||Labcorp|
|Tryptase||Serum or Plasma||Tryptase is often ordered as part of the diagnostic assessment of a patient suspected of having mastocytosis (either cutaneous or systemic).3-5 Serum levels are thought to correlate with mast cell "burden" in these patients.5 Mastocytosis is considered in the differential diagnosis of patients that experience severe allergic reactions without any identifiable specific trigger. Systemic mastocytosis can produce symptoms suggestive of organ involvement, such as peptic ulcers, chronic diarrhea, and joint pain. These patients may display evidence of enlargement of the liver, spleen, or lymph nodes. There may be skin involvement with rashes or characteristic red blistering lesions.
Tryptase may be ordered to help confirm anaphylaxis as the cause of an individual's acute symptoms, especially when the diagnosis is not clear and/or the symptoms are recurrent.6,7 With anaphylaxis, tryptase levels typically peak about one to two hours after symptoms begin and then decline slowly within the next three to six hours. The biological half-life for tryptase is about two hours.
Systemic mastocytosis is a risk factor for anaphylactic reactions, particularly in response to drugs8,9 and insect stings.10-15 Patients with elevated baseline tryptase levels may be at increased risk for severe anaphylactic reactions. The risk associated with baseline elevated tryptase levels is greater in individuals with a known history of severe systemic reactions. Transiently increased tryptase levels measured during severe reaction to an allergen, such as insect venom or an anesthetic drug, suggest that mast cell activation may have had a role in causing the reaction.
Pathological increased levels of tryptase reflect the mast cell burden in certain hematological abnormalities and neoplasms, irrespective if systemic mastocytosis is established or not.16 Hematological disorders that involve uncontrolled growth of immature myeloid cells in the bone marrow and/or the circulation can produce increased serum tryptase levels. Several therapeutic drugs have been developed for cytoreductive therapy of systemic mastocytosis and hematological neoplasms.17 During treatment tryptase measurements is a useful monitoring and prognostic tool.
Related[edit | edit source]
See also[edit | edit source]
- US ME/CFS Clinician Coalition: Guidance on Diagnosis and Management
- The Mast Cell Disease Society: Tests for Mast Cell Activation
References[edit | edit source]
α - Greek letter alpha or alfa (symbol)
assay - 1. (verb) analysis (as of an ore or drug) to determine the presence, absence, or quantity of one or more components. 2. (noun) In biochemistry, any laboratory protocol used to test a sample for one or more qualities.
plasma - The liquid part of blood, lymph, or milk after removing any suspended material. Most of the time, "plasma" simply refers to blood, after all the blood cells have been removed. If you also remove the clotting factors, then the plasma is referred to as "serum".
anaphylaxis - "an often severe and sometimes fatal systemic reaction in a susceptible individual upon exposure to a specific antigen (such as wasp venom or penicillin) after previous sensitization". Typically causes breathing problems, fainting or loss of consciousness, fast heartbeat, itching, and hives. (Learn more: www.nhs.uk)