Blood – Special Tests
Determination of Erythrocyte Sedimentation Rate (ESR)
When anti–coagulated blood is allowed to stand undisturbed for some time, the red blood cells start to settle down. The rate at which red blood cells settle down is known as the Erythrocyte sedimentation rate.
It is done by three methods:
- Westergren’s method.
- Wintrobe’s method.
- Micro–sedimentation (Landau) method.
Normal Range
| Method |
Male |
Female |
| Westergren’s method |
0–15 mm. after 1st hour |
0–20 mm. after 1 hour |
| Wintrobe’s method |
0–9 mm.after 1st hour |
0–20 mm. after 1 hour |
| Landau method |
0–5 mm after 1st hour |
0–8 mm after 1 hour |
- ESR is increased in infections like tuberculosis, rheumatic fever, myeloma, Kala Azar, other chronic infections.
- ESR is greater in women than men due to difference in PCV (Packed Cell Volume).
- In certain anemias, ESR gradually increases after the third month and returns to normal after three to four weeks after delivery.
- ESR is low in infants and gradually increases as the child grows to puberty.
- The determination of ESR is useful in checking the progress of disease. The changes of ESR are not diagnostically of any specific disease.
Determination of Platelet Count
To investigate bleeding disorders, determination of platelets is required.
Normal range: 2,50,000 – 5,00,000/cu mm (ml).
Many times prolonged bleeding and poor clot formation is due to Thrombocytopenia (decreased platelet count).
It is also found in aplastic anemia, megaloblastic anemia, hypersplenism and acute leukemia.
Thrombocytosis (increased platelet count) is found in polycythemia vera, following splenectomy and in chronic myelogenous leukemia.
Splenectomy – is the surgical removal of the spleen.
Hypersplenism – in this spleen is enlarged.
Meaning of other terms is given in routine blood tests.
Determination of Reticulocyte Count
It is done to determine red cell forming activity of the bone marrow.
Normal Range:
- Adults – 0.2 to 2%.
- Infants – 2 to 6%.
- Reticulocyte is a precursor of Red Blood Cells (RBCs). Reticulocyte count is reflection or erythropoetic activity (red blood cell forming activity) of the bone marrow.
- Increase in the number of reticulocyte indicates increased activity of the bone marrow, in hemolytic anemia or acute blood loss. It is known as reticulocytosis.
- Absence or low count of reticulocytes indicates bone marrow suppression in aplastic anemia.
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