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blood type | Blood test to determine the blood type (A, B, AB, or O) and Rh factor (positive or negative) of the patient's blood. Type and crossmatch is done when a patient needs to receive a blood transfusion. The donor's blood type was determined when it was stored in the blood bank. The patient's (recipient's) blood type is determined. Then the patient's plasma is crossmatched by mixing it with the donor's red blood cells. If the donor's red blood cells clump together (agglutination), the blood types are not compatible.

complete blood count (CBC) with differential | Group of blood tests that are performed automatically by machine to determine the number, type, and characteristics of various cells in the blood (see Table 6-4). This is also known as a CBC with diff.

peripheral blood smear | Blood test done manually to examine the characteristics of erythrocytes and leukocytes under a microscope. A drop of blood is spread as a thin smear on a glass slide. Then hematoxylin and eosin dyes are used to stain the blood cells. A blood smear is used to investigate abnormal blood cells discovered on the automated CBC, or a blood smear can be ordered by the physician when there is reason to suspect blood cell abnormalities.

erythrocytes (red blood cells, RBCs) | Number in millions per milliliter (mL) of blood

hematocrit (HCT) | Percentage of RBCs in a blood sample

hemoglobin (Hgb) | Amount in grams per deciliter (g/dL) of blood

mean cell volume (MCV) | Average volume of one RBC

mean cell hemoglobin (MCH) | Average weight of hemoglobin in one RBC

mean cell hemoglobin concentration (MCHC) | Average concentration of hemoglobin in one RBC

leukocytes (white blood cells, WBCs) | Number in thousands per milliliter (k/mL) of blood

WBC differential | Percentage of each type of WBC per 100 WBCs

neutrophils | Percentage of each type of WBC per 100 WBCs

eosinophils | Percentage of each type of WBC per 100 WBCs

basophils | Percentage of each type of WBC per 100 WBCs

lymphocytes | Percentage of each type of WBC per 100 WBCs

monocytes | Percentage of each type of WBC per 100 WBCs

thrombocytes (platelets) | Number in thousands per milliliter (k/mL) of blood

activated clotting time (ACT) | Blood test to monitor the effectiveness of the anticoagulant drug heparin when it is given in high doses. A prolonged (rather than normal) activated clotting time would be expected.

partial thromboplastin time (PTT) | Blood test to monitor the effectiveness of the anticoagulant drug heparin when it is given in regular doses. A prolonged (rather than normal) PTT would be expected. An activated partial thromboplastin time (aPTT) test uses a chemical activator to get faster test results.

prothrombin time (PTT) | Blood test to evaluate the effectiveness of the anticoagulant drug Coumadin. A prolonged (rather than normal) PT would be expected. The international normalized ratio (INR) reports the PT value in a standardized way, regardless of which laboratory performed the test.

blood chemistries | Blood test used to determine the levels of various substances in the blood (see Figure 6-20). These include electrolytes, albumin, total protein, ALT, AST, BUN, creatinine, bilirubin, glucose, LDH, total cholesterol, uric acid, and alkaline phosphatase. A Chem-20 includes 20 individual chemistry tests performed at the same time. This is also called a metabolic panel.

ferritin | Blood test that indirectly measures the amount of iron (ferritin) stored in the body by measuring the small amount that is always present in the blood. The total iron-binding capacity (TIBC) measures the level of transferrin, a protein that carries iron in the blood. These tests are used to diagnose iron deficiency anemia.

human immunodeficiency virus (HIV) tests | Blood tests that detect infection with HIV. HIV tests are reported as either HIV negative or HIV positive.

ELISA | First screening test done for HIV. It can be done on blood, urine, or saliva samples. The test uses two antibodies. The first binds to HIV, forming a complex; the second reacts to an enzyme in that complex. However, this test can also be positive if the patient has antibodies against lupus erythematosus, Lyme disease, or syphilis. ELISA stands for enzyme-linked immunosorbent assay. The test results are available in 1–2 weeks; however, the SUDS (Single-Use Diagnostic System) test, which uses ELISA methods, is a rapid HIV test that gives results in 10 minutes. OraSure is a quick screening test done in a doctor's office or clinic to detect antibodies to HIV in the saliva.

Western blot | Used to confirm a positive ELISA and make a diagnosis of HIV infection. A positive ELISA and a positive Western blot together are 99.9% accurate in diagnosing HIV infection.

viral RNA load test | Measures tiny amounts of RNA (from HIV) that are in the blood during the 6 weeks before antibodies against HIV can be detected. This test is also used to monitor the progression of the disease and the patient's response to antiretroviral drugs.

p24 antigen test | Detects p24, a protein in HIV. The results are reported as a titer. This test is also used to screen donated units of blood for HIV.

CD4 count | Measures the number of CD4 lymphocytes (helper T cells). It is used to monitor the progression of the disease and the patient's response to antiretroviral drugs. The CD4:CD8 ratio is also monitored.

MonoSpot test | Rapid test that uses the patient's serum mixed with horse erythrocytes. If the patient has infectious mononucleosis, heterophil antibodies in the patient's serum cause the horse's erythrocytes to clump. It is also called the heterophil antibody test.

serum protein electrophoresis (SPEP) | Immunoglobulin electrophoresis test that determines the amount of each immunoglobulin (IgA, IgD, IgE, IgG, and IgM) in the blood. A sample of serum is placed in a gel with an electrical current. The immunoglobulins become charged and move toward the positive or negative electrode. Each immunoglobulin travels a different distance and direction through the gel, depending on its size and charge, and it appears as a spike in a different area on the graph paper. The size of the spike corresponds to how much immunoglobulin is present.

Bence Jones protein | Urine test, also known as urine protein electrophoresis (UPEP), that is used to monitor the course of multiple myeloma. The cancerous plasma cells produce this abnormal immunoglobulin that can be detected in the urine.

Schilling test | Urine test used to diagnose pernicious anemia. It measures the amount of radioactive vitamin B12 excreted in the urine. The patient swallows a capsule that contains intrinsic factor and vitamin B12 labeled with a radioactive tracer. The patient swallows a second capsule that contains vitamin B12 labeled with a different radioactive tracer but no intrinsic factor. If the patient has pernicious anemia, only the capsule that contained vitamin B12 and intrinsic factor will be absorbed into the blood and then excreted in the urine.

lymphangiography | Radiologic procedure in which a radiopaque contrast dye is injected into a lymphatic vessel. X-rays are taken as the dye travels through the lymphatic vessels and lymph nodes. It shows enlarged lymph nodes, lymphomas, and areas of blocked lymphatic drainage. The x-ray image is a lymphangiogram.