Ch.15 Blood/Genetic Testing

Blood Tests Overview

Blood tests provide essential insights into health and are critical for diagnosing medical conditions. Tests are often grouped into profiles or panels, completed using automated laboratory equipment.

Blood Specimen Collection Methods

  • Phlebotomy: Equipment punctures a vein to draw blood.

  • Arterial Stick: Punctures an artery, typically at the wrist, to obtain arterial blood, which differs from venous blood mainly in gas content.

  • Capillary Puncture: Small samples obtained through finger, heel, or earlobe sticks.

Complete Blood Cell Count (CBC)

A CBC assesses various blood conditions through several tests:

  • Erythrocyte Sedimentation Rate (ESR): Measures how quickly red blood cells settle; elevated rates indicate inflammation.

  • Hematocrit (Hct): Percentage of total blood volume occupied by red blood cells, helpful for assessing anemia or polycythemia.

  • Platelet Count: Screens for thrombocytosis (increase) or thrombocytopenia (decrease) in platelets.

  • Red Blood Cell Count (RBC): Low counts suggest anemia or blood loss.

  • Total Hemoglobin (Hb) Test: Indicates hemoglobin concentration; high levels may point to polycythemia, while low levels indicate anemia.

  • White Blood Cell Count (WBC): Elevated leukocyte counts often suggest infection.

  • White Blood Cell Differential Count: Analyzes percentages of leukocyte types to assess immune status and detect leukemia.

Additional Blood Tests

  • Basic Metabolic Panel (BMP): Includes eight tests for kidney function and electrolyte balance; abnormalities may indicate acute issues.

  • Blood Urea Nitrogen (BUN) Test: Indicates kidney function through urea nitrogen levels.

  • Crossmatch Tests: Assess blood compatibility for transfusions; agglutination shows incompatibility.

  • C-Reactive Protein (CRP) Test: Measures inflammation; high levels may suggest heart disease or autoimmune issues.

  • Lipid Panel: Evaluates cholesterol and triglycerides for cardiovascular risk.

  • Prothrombin Time (PT): A coagulation test for clotting abnormalities; prolonged time may signal liver disease.

  • Serum Bilirubin Test: Assesses liver function by measuring bilirubin processing.

  • Thyroid Stimulating Hormone (TSH) Assay: Evaluates thyroid activity levels.

  • Arterial Blood Gas Analysis (ABG): Measures pH, oxygen, and carbon dioxide to assess lung and kidney function.

  • Genetic Testing: Analyzes blood, saliva, and tissues for gene variants linked to disease risks, including BRCA gene testing and newborn screenings.