Physiological Variations in Haematological parameters, including haemoglobin (Hb), packed cell volume (PCV), total leukocyte count (TLC), and platelet count, are essential indicators of overall health and well-being. These parameters can vary significantly among individuals due to various physiological factors, including age, sex, altitude, and underlying medical conditions.
Haemoglobin (Hb)
Haemoglobin, a protein found in red blood cells, carries oxygen from the lungs to the tissues. Normal Hb levels vary slightly between individuals and can be influenced by several factors:
- Age: Newborn infants have higher Hb levels than adults, gradually decreasing.
- Sex: Males typically have slightly higher Hb levels than females due to differences in body composition.
- Altitude: Individuals living at high altitudes often have higher Hb levels to compensate for the reduced oxygen availability.
- Pregnancy: Hb levels may decrease slightly during pregnancy due to increased blood volume.
- Medical conditions: Certain conditions, such as anaemia, can cause significantly lower Hb levels.
Packed Cell Volume (PCV)
PCV is the percentage of red blood cells in a given blood volume. It is closely related to Hb levels and is often used to measure anaemia. Factors that influence PCV include:
- Age, sex, and altitude: Similar to Hb, PCV varies with these factors.
- Dehydration: Dehydration can lead to a falsely elevated PCV due to decreased plasma volume.
- Polycythemia: Polycythemia, a condition characterized by an abnormally high number of red blood cells, can result in an elevated PCV.
Total Leukocyte Count (TLC)
TLC is the number of white blood cells in a given blood volume. White blood cells play a crucial role in the immune system, fighting infections and foreign invaders. Factors that can influence TLC include:
- Infection: During infections, TLC often increases as the body produces more white blood cells to combat the invading pathogens.
- Stress: Emotional or physical stress can temporarily elevate TLC.
- Medications: Certain medications, such as corticosteroids, can affect TLC.
- Medical conditions: Some conditions, such as leukaemia, can lead to abnormally high or low TLC.
Platelet Count
Platelets are small cell fragments that play a vital role in blood clotting. A normal platelet count is essential for preventing excessive bleeding. Factors that can influence platelet count include:
- Medications: Certain medications, such as aspirin and anticoagulants, can reduce platelet count.
- Medical conditions: Some medical conditions, such as thrombocytopenia, can cause a low platelet count, while others, such as polycythemia vera, can lead to a high platelet count.
- Bone marrow disorders: Disorders of the bone marrow, where platelets are produced, can affect platelet count.