Haematological Indices

Introduction to Haematological Indices

• Haematological indices are part of the full blood count test report.
• They play a vital role in diagnosing disease conditions such as anaemia, cancers, etc.
• They are simple, inexpensive, and practical severity markers for disease conditions.
• They can be grouped into Red Blood Cell (RBC) indices and Platelet indices.

Red Blood Cell Indices

• RBC indices provide information about the haemoglobin content and size of red blood cells.
• Abnormal values indicate the presence of anaemia and its type.
• There are four types of RBC indices:
  • Mean Corpuscular Volume (MCV) - measures the average size of red blood cells.
  • Mean Corpuscular Haemoglobin (MCH) - measures the average amount of haemoglobin in a single red blood cell.
  • Mean Corpuscular Haemoglobin Concentration (MCHC) - measures haemoglobin in red blood cells.
  • Red Cell Distribution Width (RDW) - measures differences in the volume and size of red blood cells.

MCV

• MCV gives an indication of whether red blood cells are normocytes, microcytes, or macrocytes.
• Normal value: 80-100 fl (femtolitre).

MCH

• MCH gives an indication of whether red blood cells are normochromic, hypochromic, or hyperchromic.
• Normal value: 28-34 pg (picogram).
• MCH increases with B12 deficiency, folic acid deficiency, and reticulocytosis.
• MCH decreases with iron deficiency anaemia, thalassaemia, and anaemia of chronic disorder.

MCHC

• MCHC measures the average concentration of haemoglobin in a deciliter of erythrocytes.
• Normal value: 32-36 g/dl.
• MCHC increases with hypochromic red blood cells.
• MCHC decreases with hyperchromic red blood cells.

Rule of Three

• A formula to interpret the accuracy of RBC count, haematocrit, and haemoglobin values.

Platelet Indices

• Platelet indices are useful markers for the early diagnosis of thromboembolic diseases.
• They consist of:
  • Plateletcrit (PCT) - measures total platelet mass.
  • Platelet Distribution Width (PDW) - reflects variability in platelet sizes.
  • Mean Platelet Volume (MPV) - measures the average size of platelets.

Plateletcrit (PCT)

• PCT is a measure of total platelet mass, occupying a percentage of blood volume.
• Normal value: 0.20 to 0.36%.

Mean Platelet Volume (MPV)

• MPV is a sign that the body is producing too many platelets.
• A high MPV indicates large platelets, associated with platelet activation.
• A low MPV indicates smaller platelets, associated with ineffective platelet formation in the bone marrow.

Platelet Distribution Width (PDW)

• PDW reflects variability in platelet sizes, associated with vascular disease or certain cancers.