Clinical Lab Tests – Easy Notes

Vocabulary-style flashcards covering key lab test concepts, values, and interpretations from the notes.

Clinical Biochemistry

Lab discipline focusing on chemistry tests such as electrolytes and proteins in blood/urine.

Hematology

Lab discipline dealing with blood cell counts (WBC, RBC, platelets) and related indices.

Microbiology

Discipline identifying bacteria, viruses, fungi, and parasites in clinical specimens.

Immunology

Study of the immune system, including autoimmune diseases and immune deficiencies.

Anatomic Pathology

Discipline analyzing tissue samples to diagnose disease.

Reference Range

Normal limits for a lab value, which vary by age, gender, race, and lab.

Critical Test Value

Abnormally high or low result that may be life-threatening and must be reported immediately.

Complete Blood Count (CBC)

Panel measuring WBC, RBC, and platelets.

WBC

White blood cell count; indicator of immune status and infection.

RBC

Red blood cell count; reflects oxygen-carrying capacity.

Platelets

Cell fragments essential for clotting; low/high levels affect bleeding/clotting risk.

Leukocytosis

High white blood cell count, often from infection, stress, or trauma.

Leukopenia

Low white blood cell count, may indicate immune suppression or marrow disease.

Neutrophils

WBC type; higher % suggests bacterial infection; lower may indicate marrow issues.

Lymphocytes

WBC type; higher % suggests viral infection; lower may indicate immune problems.

CD4 T-cells

Subset of lymphocytes; decreased in HIV; counts <200 cells/µL raise AIDS risk.

Eosinophils

WBC type elevated in allergies or parasitic infections.

Basophils

WBC type often increased in allergies.

Monocytes

WBC type; elevated with foreign material invasion or certain infections.

Hemoglobin (Hb)

Protein in red blood cells that carries oxygen.

Hematocrit (Hct)

Percentage of blood volume occupied by red blood cells.

RBC Count (Men)

Normal range for men; part of CBC assessment.

RBC Count (Women)

Normal range for women; part of CBC assessment.

Anemia

Low RBC count or Hb/Hct indicating reduced oxygen-carrying capacity.

Polycythemia

Elevated RBC count indicating increased red cell mass, often due to hypoxia or other conditions.

Hemoglobin Normal Range (Men)

Hb typically 13.3–17.7 g/dL in men.

Hemoglobin Normal Range (Women)

Hb typically 11.7–15.7 g/dL in women.

Hematocrit Normal Range (Men)

Hct typically 40–52% in men.

Hematocrit Normal Range (Women)

Hct typically 35–47% in women.

Electrolytes

Key ions and related compounds measured in chemistry panels (Na+, K+, Cl-, CO2, Ca2+, glucose, etc.).

Sodium (Na+)

Normal 136–145 mEq/L; values

Potassium (K+)

Normal 3.5–5.0 mEq/L; values

Chloride (Cl-)

Normal 98–106 mEq/L; abnormal

CO2 / Bicarbonate

Normal 22–29 mEq/L; abnormal

Calcium (Ca2+)

Total calcium normal range 4.5–5.25 mEq/L; abnormal

Ionized Calcium (Ca2+)

Active calcium; normal 2.2–2.7 mEq/L; abnormal

Glucose

Normal 70–139 mg/dL; >200 with symptoms suggests diabetes.

Anion Gap

Normal 4–12 mmol/L; higher values suggest metabolic acidosis.

Lactate

Normal 0.7–2.1 mEq/L; >4 indicates tissue hypoxia or sepsis.

ALT

Liver enzyme; elevated levels indicate liver injury/damage.

AST

Liver enzyme; elevated levels indicate liver injury/damage.

Bilirubin

Liver-related pigment; elevated with liver dysfunction or hemolysis.

Albumin

Liver-produced protein; low levels suggest liver disease or malnutrition.

Amylase

Pancreatic enzyme; elevated in pancreatitis.

Lipase

Pancreatic enzyme; elevated in pancreatitis.

CK (CPK) Isoenzymes

Creatine kinase isoenzymes indicate tissue injury: CK-BB (brain), CK-MB (heart), CK-MM (skeletal muscle).

Troponin-I

Cardiac muscle protein; elevated in myocardial infarction.

BNP

B-type natriuretic peptide; elevated in heart failure; very high values suggest severe failure.

Procalcitonin (PCT)

Biomarker; <0.1 ng/mL is normal; around 0.5 ng/mL suggests sepsis likely.

PT/INR

Coagulation tests; PT/INR normal ~0.9–1.3; markedly high INR indicates bleeding risk.

D-Dimer

Fibrin degradation product; elevated with clots (DVT, PE, DIC).

Protein C

Protein C; regulates clot breakdown; deficiency increases clot risk.

Sputum Gram Stain

Microscopic test to identify bacteria type and shape in sputum.

Culture

Laboratory grow-out to identify organism and antibiotic sensitivity.

Acid-Fast Test (AFB)

Stain used to detect acid-fast organisms like Mycobacterium tuberculosis.

Xpert MTB/RIF

Rapid molecular TB test that also detects rifampin resistance.

NAAT

Nucleic Acid Amplification Test; detects genetic material of pathogens.

Viral Testing

Tests using antigen or molecular assays to detect viruses.

Sweat Chloride Test

Measures chloride in sweat; 60 mmol/L is typical CF indicator; 30–60 is borderline; <29 unlikely CF.

Cystic Fibrosis (CF) Test

Diagnostic use of sweat chloride testing for CF evaluation.

Clinical Application of Lab Tests

Guides care: check coagulation before ABG/suctioning; manage severe electrolyte imbalances affecting muscles, breathing, and infection risk.