Interpreting Clinical Laboratory Tests - Vocabulary Flashcards

A set of vocabulary-style flashcards covering key terms and definitions from the lecture notes on clinical laboratory tests.

Reference range

The boundaries for the expected variability of an analyte in healthy patients, with adjustments for age, gender, race, and laboratory differences.

Critical test value

A result far outside the reference range indicating a potentially life-threatening condition; must be communicated promptly and documented.

Complete Blood Count (CBC)

A common test that measures formed elements of blood: white cells, red cells, and platelets.

Leukocytes (white blood cells, WBCs)

Cells of the immune system counted in CBCs and analyzed in a differential.

Erythrocytes (red blood cells, RBCs)

Cells that carry oxygen; evaluated for size and hemoglobin content in CBCs.

Thrombocytes (platelets)

Small blood cells evaluated by count, important for clotting.

Leukocytosis

WBC count above the normal range, often seen with infection, stress, or trauma.

Leukopenia

WBC count below the normal range, seen with overwhelming infection or bone marrow suppression.

Neutrophils

Most common type of WBC; relative 40-75% of WBCs; absolute count 1.8-6.8 x10^9/L.

Neutrophilia

Elevated neutrophil count, often indicating bacterial infection or inflammation.

Bands

Immature neutrophils; elevation suggests increased marrow production during infection.

Segs (segmented neutrophils)

Mature neutrophils; part of the differential count.

Lymphocytes

WBCs involved in adaptive immunity; relative 20-45%; absolute 1.0-3.4 x10^9/L.

CD4 T lymphocytes

Subset of lymphocytes essential in immune response; relative 31-60%; absolute 410-1590 x10^6/L; HIV threshold <200.

Eosinophils

WBCs involved in allergic responses and parasitic infections; relative 0-6%.

Basophils

WBCs involved in allergic reactions; relative 0-1%.

Monocytes

WBCs involved in phagocytosis; relative 2-10%.

Red Blood Cell Count (RBC)

Number of RBCs in a volume of blood; low counts indicate anemia; high counts indicate polycythemia.

Anemia

Condition with reduced RBCs or hemoglobin, reducing oxygen delivery.

Polycythemia

Elevated RBC count; may be primary or secondary (e.g., to hypoxemia).

Hemoglobin (Hb)

Oxygen-carrying protein in RBCs; normal ranges differ by sex.

Hemoglobinopathy (microcytic, hypochromic)

RBCs that are small (microcytic) and pale (hypochromic) often seen in iron deficiency anemia.

Hematocrit

Proportion of blood volume occupied by RBCs; relative to normal ranges by sex.

Basic Chemistry Panel (BMP)

A panel of measures including electrolytes (Na, K, Cl, CO2), glucose, and renal waste products (creatinine, BUN).

Sodium (Na+)

Major extracellular cation; maintains fluid balance and nerve conduction; normal 136-145 meq/L.

Hypernatremia

High sodium; often from dehydration or excess saline administration.

Hyponatremia

Low sodium; can result from overhydration or ADH issues among other causes.

Potassium (K+)

Major intracellular cation; crucial for cardiac and muscle function; normal 3.5-5.0 meq/L.

Hyperkalemia

High potassium; can be life-threatening and seen in kidney disease or cell breakdown.

Hypokalemia

Low potassium; can cause weakness and arrhythmias, seen with vomiting/diarrhea.

Chloride (Cl−)

Extracellular anion important for osmolarity and acid-base balance; normal 98-106 meq/L.

Hyperchloremia

High chloride; may occur with saline resuscitation or metabolic acidosis.

Hypochloremia

Low chloride; can accompany vomiting, diarrhea, or metabolic alkalosis.

Total CO2 / bicarbonate (HCO3−)

Metabolic component of acid-base balance; part of BMP; normal 22-29 meq/L.

Anion Gap

Na+ − (Cl− + HCO3−); normal 4-12 mmol/L; helps identify metabolic acidosis and albumin status.

Lactate

End product of anaerobic glucose metabolism; elevated levels indicate hypoxia or shock; normal 0.7-2.1 meq/L (in notes).

Liver Function Tests (LFTs)

Panel including bilirubin, total protein, and albumin to assess liver function.

Total Bilirubin (TBIL)

Bilirubin measure included in LFTs; helps assess liver and biliary function.

Total Protein (TP) and Albumin (ALB)

Measures of protein synthesis and nutritional status; albumin reflects liver function and nutrition.

Pancreatic and Muscle Enzymes

Amylase, lipase (pancreatic); creatine phosphokinase (CPK) and lactate dehydrogenase (LD) reflect tissue injury.

CPK Isoforms

Different forms: CPK-BB (CPK-1) from brain/lung, CPK-MB (CPK-2) from heart, CPK-MM (CPK-3) from skeletal muscle.

Troponin-I

Cardiac-specific protein; rises after MI and peaks 12-48 hours post-event.

BNP (B-type Natriuretic Peptide)

Marker of heart failure severity; higher values indicate worse dysfunction.

Coagulation Studies

Tests of clotting function including PT, PTT, INR, and platelet count.

Prothrombin Time (PT)

Time for plasma to clot via the extrinsic pathway; used with INR.

Partial Thromboplastin Time (PTT)

Time for plasma to clot via the intrinsic pathway; used with PT/INR to assess coagulation.

INR (International Normalized Ratio)

Standardized PT value; typical range 0.9-1.3; higher values indicate bleeding risk.

D-Dimer

Fragment produced when clots dissolve; helps diagnose DVT, PE, or DIC.

Protein C / Activated Protein C (APC)

Protein that regulates coagulation; APC promotes anticoagulation and clot breakdown.

Procalcitonin (PCT)

Biomarker of bacterial infection;

Sputum Gram Stain

Microscopy to classify organisms as Gram-positive or Gram-negative and shape, using sputum quality indicators.

Sputum Culture

Growth of organisms from sputum to identify pathogens and guide antibiotic therapy.

Acid-fast Testing (TB)

Stain and identification for Mycobacterium tuberculosis; acid-fast organisms resist decolorization.

Xpert MTB/RIF

Automated rapid molecular test for TB that also detects rifampin resistance within about 2 hours.

Viral Testing (NAAT and antigen tests)

Tests detecting viral DNA/RNA or antigens; used for diagnosis of viral infections; may include serology.

Sweat Chloride Test

Test for cystic fibrosis; chloride concentration in sweat; >60 mmol/L supports CF diagnosis; 30-60 borderline; <29 unlikely.

Acid-fast bacillus (AFB)

Bacteria that retain the acid-fast stain, notably Mycobacterium species.

Reference range

The boundaries for the expected variability of an analyte in healthy patients, with adjustments for age, gender, race, and laboratory differences.

Critical test value

A result far outside the reference range indicating a potentially life-threatening condition; must be communicated promptly and documented.

Complete Blood Count (CBC)

A common test that measures formed elements of blood: white cells, red cells, and platelets.

Leukocytes (white blood cells, WBCs)

Cells of the immune system counted in CBCs and analyzed in a differential.

Erythrocytes (red blood cells, RBCs)

Cells that carry oxygen; evaluated for size and hemoglobin content in CBCs.

Thrombocytes (platelets)

Small blood cells evaluated by count, important for clotting.

Leukocytosis

WBC count above the normal range, often seen with infection, stress, or trauma.

Leukopenia

WBC count below the normal range, seen with overwhelming infection or bone marrow suppression.

Neutrophils

Most common type of WBC; relative 40-75% of WBCs; absolute count 1.8-6.8 \times 10^9/L

Neutrophilia

Elevated neutrophil count, often indicating bacterial infection or inflammation.

Bands

Immature neutrophils; elevation suggests increased marrow production during infection.

Segs (segmented neutrophils)

Mature neutrophils; part of the differential count.

Lymphocytes

WBCs involved in adaptive immunity; relative 20-45%; absolute 1.0-3.4 \times 10^9/L

CD4 T lymphocytes

Subset of lymphocytes essential in immune response; relative 31-60%; absolute 410-1590 \times 10^6/L; HIV threshold <200

Eosinophils

WBCs involved in allergic responses and parasitic infections; relative 0-6%.

Basophils

WBCs involved in allergic reactions; relative 0-1%.

Monocytes

WBCs involved in phagocytosis; relative 2-10%.

Red Blood Cell Count (RBC)

Number of RBCs in a volume of blood; low counts indicate anemia; high counts indicate polycythemia.

Anemia

Condition with reduced RBCs or hemoglobin, reducing oxygen delivery.

Polycythemia

Elevated RBC count; may be primary or secondary (e.g., to hypoxemia).

Hemoglobin (Hb)

Oxygen-carrying protein in RBCs; normal ranges differ by sex.

Hemoglobinopathy (microcytic, hypochromic)

RBCs that are small (microcytic) and pale (hypochromic) often seen in iron deficiency anemia.

Hematocrit

Proportion of blood volume occupied by RBCs; relative to normal ranges by sex.

Basic Chemistry Panel (BMP)

A panel of measures including electrolytes (Na, K, Cl, CO2), glucose, and renal waste products (creatinine, BUN).

Sodium (Na+)

Major extracellular cation; maintains fluid balance and nerve conduction; normal 136-145 \text{ meq/L}

Hypernatremia

High sodium; often from dehydration or excess saline administration.

Hyponatremia

Low sodium; can result from overhydration or ADH issues among other causes.

Potassium (K+)

Major intracellular cation; crucial for cardiac and muscle function; normal 3.5-5.0 \text{ meq/L}

Hyperkalemia

High potassium; can be life-threatening and seen in kidney disease or cell breakdown.

Hypokalemia

Low potassium; can cause weakness and arrhythmias, seen with vomiting/diarrhea.

Chloride (Cl−)

Extracellular anion important for osmolarity and acid-base balance; normal 98-106 \text{ meq/L}

Hyperchloremia

High chloride; may occur with saline resuscitation or metabolic acidosis.

Hypochloremia

Low chloride; can accompany vomiting, diarrhea, or metabolic alkalosis.

Total CO2 / bicarbonate (HCO3−)

Metabolic component of acid-base balance; part of BMP; normal 22-29 \text{ meq/L}

Anion Gap

Na+ − (Cl− + HCO3−); normal 4-12 \text{ mmol/L} ; helps identify metabolic acidosis and albumin status.

Lactate

End product of anaerobic glucose metabolism; elevated levels indicate hypoxia or shock; normal 0.7-2.1 \text{ meq/L} (in notes).

Liver Function Tests (LFTs)

Panel including bilirubin, total protein, and albumin to assess liver function.

Total Bilirubin (TBIL)

Bilirubin measure included in LFTs; helps assess liver and biliary function.

Total Protein (TP) and Albumin (ALB)

Measures of protein synthesis and nutritional status; albumin reflects liver function and nutrition.

Pancreatic and Muscle Enzymes

Amylase, lipase (pancreatic); creatine phosphokinase (CPK) and lactate dehydrogenase (LD) reflect tissue injury.

CPK Isoforms

Different forms: CPK-BB (CPK-1) from brain/lung, CPK-MB (CPK-2) from heart, CPK-MM (CPK-3) from skeletal muscle.

Troponin-I

Cardiac-specific protein; rises after MI and peaks 12-48 hours post-event.

BNP (B-type Natriuretic Peptide)

Marker of heart failure severity; higher values indicate worse dysfunction.