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Disease Topics — Thrombocytopenia is a common clinical condition with a broad differential diagnosis, and identifying its etiology involves careful assessment of both clinical characteristics and the results of well-chosen laboratory tests. Thrombocytopenic disorders include numerous causes of decreased…
Indications for TestingTesting for thrombocytopenic disorders should be considered in patients with platelet counts <100-150 x 109/L.
Disease Topics — Hemophilia A and hemophilia B are bleeding disorders caused by genetic variants in the F8 or F9 gene that result in deficiencies of factor VIII in hemophilia A or factor IX in hemophilia B, respectively. These disorders are clinically indistinguishable and present with bleeding symptoms that…
Indications for TestingHemophilia testing is warranted in individuals with spontaneous bleeding (particularly into joints, muscles, and soft tissues) or prolonged/excessive bleeding that is suggestive of a coagulation disorder. Common bleeding manifestations include epistaxis, hemarthroses,…
Disease Topics — Thyrotoxicosis, a clinical state with serious adverse health consequences that results from excess thyroid hormone action in tissues, is often caused by elevated thyroid hormone concentrations. Hyperthyroidism is a form of thyrotoxicosis that results from the overproduction and oversecretion of…
Indications for TestingLaboratory testing for hyperthyroidism is appropriate in individuals with:
Disease Topics — T-cell and natural killer (NK)-cell lymphomas are a rare subset of non-Hodgkin lymphomas (NHLs) that originate from T cells and NK cells. T-cell and NK-cell lymphomas are classified based on characteristics such as site of presentation (i.e., hematolymphoid, cutaneous, gastrointestinal tract…
ClassificationThe World Health Organization (WHO) and the International Consensus Classification (ICC) have classification systems for T-cell and NK-cell lymphomas that integrate the site of presentation (i.e., hematolymphoid, cutaneous, gastrointestinal tract, liver, or spleen) with morphologic,…
Disease Topics — Primary membranous nephropathy (PMN) is a kidney-specific autoimmune disease that is caused by circulating antibodies against certain native podocyte antigens, specifically phospholipase A2 receptor (PLA2R) and thrombospondin type-1 domain-containing 7A (THSD7A). , PMN is characterized…
Indications for TestingTesting for antibodies that may cause PMN should be considered in patients who present with idiopathic nephrotic syndrome (proteinuria >3.0 g/d, hypoalbuminemia, edema, hyperlipidemia and lipiduria, and normal or slightly altered kidney function). ,
Disease Topics — Mature B-cell non-Hodgkin lymphomas (NHLs) are a heterogeneous group of clonal hematologic malignancies involving mature B cells. The diagnostic approach to mature B-cell lymphomas generally involves morphologic evaluation of a biopsy, preferably excisional or incisional, and…
ClassificationThe World Health Organization (WHO) and the International Consensus Classification (ICC) have classification systems for B-cell lymphomas that integrate morphologic, immunophenotypic, genetic, and clinical features. ,
Disease Topics — Preeclampsia is a pregnancy-related multisystem progressive disorder characterized by hypertension (systolic blood pressure [BP] ≥140 mmHg and/or diastolic BP ≥90 mmHg) and one or more additional signs of physiologic dysfunction. Preeclampsia typically occurs after 20 weeks of gestation, usually…
Indications for TestingInitial risk assessment for preeclampsia is indicated in all pregnant individuals, regardless of preeclampsia risk status. Baseline testing is recommended in pregnant individuals at first diagnosis of chronic hypertension.
Disease Topics — The Treponema pallidum subspecies pallidum is the etiologic agent of syphilis. Syphilis is usually transmitted sexually, but it can also be passed vertically from mother to child either in utero (congenital syphilis) or perinatally during birth. , Regardless of the mode of transmission,…
Indications for TestingPersons with signs or symptoms of syphilis infection should be tested. Additionally, asymptomatic individuals at high risk for syphilis (or of transmitting the disease to others) should be screened for infection. This includes pregnant individuals, individuals with a sexual…
Disease Topics — Tickborne diseases, including Lyme disease and Rocky Mountain spotted fever, are increasing in incidence and distribution in the United States. Tickborne diseases are transmitted to humans through the bite of an infected tick, and infections typically occur during the summer months, when ticks are…
Indications for TestingIn general, tickborne disease may be suggested by a combination of clinical presentation and supportive travel history, activity, or geographic area of residence. Some tickborne diseases present with telltale symptoms; for example, individuals with Lyme disease typically have…
Disease Topics — Calcium imbalance (hyper- or hypocalcemia) is a metabolic abnormality with widespread effects that may be acute or chronic. Mild cases may be asymptomatic, whereas acute, severe hyper- or hypocalcemia may present with musculoskeletal, gastrointestinal, cardiovascular, neurologic, or psychiatric…
Indications for TestingLaboratory testing for calcium and vitamin D is used to: