13. INTRODUCTION TO PATHOLOGY OF BLOOD AND URINE

Pathology of Blood and Urine

Pathology of blood and urine helps in diagnosing a wide range of diseases. Blood contains different types of cells with specific functions, while urine reflects kidney function and metabolic status. These notes explain the roles of lymphocytes and platelets, abnormal red blood cells (RBCs) and the clinical significance of normal and abnormal urine constituents in simple, student-friendly language.

Lymphocytes and Platelets: Their Role in Health and Disease

Lymphocytes

Lymphocytes are a type of white blood cell (WBC) essential for immunity. They protect the body from infections, viruses, bacteria and foreign substances. Lymphocytes are of two main types:

1. B-Lymphocytes (B-Cells)

• Produce antibodies that neutralize pathogens.
• Provide long-term immunity after vaccination or infection.

2. T-Lymphocytes (T-Cells)

• Helper T cells: Activate other immune cells.
• Cytotoxic T cells: Kill virus-infected and cancer cells.
• Regulatory T cells: Prevent autoimmune diseases.

Clinical significance of abnormal lymphocyte count

• High lymphocytes (Lymphocytosis): Viral infections (COVID-19, hepatitis), tuberculosis, leukemia.
• Low lymphocytes (Lymphocytopenia): HIV infection, steroid therapy, autoimmune disorders, malnutrition.

Platelets

Platelets (thrombocytes) are small blood fragments that help stop bleeding by forming clots.

Functions of Platelets

• Initiate blood clotting (hemostasis).
• Help repair damaged blood vessels.
• Prevent excessive bleeding after injury.

Clinical significance of abnormal platelet count

• Thrombocytopenia (Low platelets): Leads to bleeding, bruises, petechiae; caused by dengue, bone marrow diseases, drugs.
• Thrombocytosis (High platelets): Increases risk of blood clots, stroke or heart attack.

Erythrocytes (RBCs): Abnormal Cells and Their Significance

Red blood cells carry oxygen throughout the body. Abnormal shapes or sizes of RBCs can indicate specific diseases.

Common Abnormal RBC Types

1. Microcytes

RBCs smaller than normal; seen in iron deficiency anemia.

2. Macrocytes

Large RBCs; found in vitamin B12 or folic acid deficiency.

3. Spherocytes

Round, sphere-shaped RBCs; seen in hereditary spherocytosis and autoimmune hemolytic anemia.

4. Target Cells

RBCs with a bull’s-eye appearance; present in thalassemia and liver disease.

5. Sickle Cells

Crescent-shaped RBCs; seen in sickle cell anemia. They block blood vessels and reduce oxygen supply.

6. Schistocytes (Fragmented cells)

Broken RBC pieces; found in hemolytic anemia and DIC (disseminated intravascular coagulation).

7. Hypochromic RBCs

Pale RBCs due to low hemoglobin; common in iron deficiency.

Clinical Significance of RBC Abnormalities

• Help diagnose types of anemia.
• Indicate nutritional deficiencies (iron, B12, folate).
• Suggest genetic disorders like thalassemia or sickle cell disease.
• Identify hemolytic conditions and bone marrow disorders.

Normal and Abnormal Constituents of Urine

Urine analysis is a simple but powerful diagnostic tool. It detects kidney diseases, metabolic problems and infections.

Normal Constituents of Urine

Normal urine contains water (95%) and dissolved substances.

• Water
• Urea – final product of protein metabolism
• Creatinine – muscle metabolism waste
• Uric acid
• Sodium, potassium, chloride
• Phosphates and sulfates

Significance of Normal Constituents

• Indicate proper kidney filtering.
• Show normal metabolic activity.
• Creatinine helps estimate kidney function.

Abnormal Constituents of Urine

1. Protein (Proteinuria)

• Indicates kidney damage or infections.
• Seen in nephrotic syndrome, diabetes, hypertension.

2. Glucose (Glycosuria)

• Common in uncontrolled diabetes mellitus.

3. Ketones (Ketonuria)

• Seen in diabetic ketoacidosis, prolonged fasting or starvation.

4. Blood (Hematuria)

• Caused by kidney stones, infections, trauma or tumors.

5. Bilirubin

• Indicates liver disease or bile obstruction.

6. Nitrites

• Suggest bacterial urinary tract infection (UTI).

7. Leucocytes (Pus cells)

• Seen in urinary infections and inflammations.

8. Casts

Cylindrical structures formed in the kidney tubules.

• RBC casts: Glomerulonephritis.
• WBC casts: Pyelonephritis.
• Hyaline casts: Mild dehydration or exercise.

Clinical Significance of Urine Analysis

• Detects kidney diseases like acute and chronic renal failure.
• Helps diagnose diabetes, liver disorders and metabolic diseases.
• Identifies urinary tract infections (UTI).
• Monitors hydration and electrolyte balance.

Summary:

Pathology of blood and urine is essential for diagnosing many diseases. Lymphocytes provide immunity, platelets help in clotting, and abnormal RBC shapes indicate specific anemias and disorders. Urine analysis reveals kidney function, diabetes, infections, and metabolic problems. Understanding these helps pharmacy students interpret lab reports and understand disease mechanisms.

ACTUAL NOTES (PDF)