What are target cells?
1 Answer
Codocytes, also known as target cells are RBC's that have the appearance of a shooting target with a bulls eye.
Explanation:
Target cells are thin RBC's that have an over abundance of cell membrane, which causes the cells to assume a bell shape while in circulation. When the cells are flattened out in a smear, the top of the bell is pushed to the centre, creating a central target or bulls eye.
In a blood film these cells appear thinner than normal, primarily due to their pallor - by which thickness is judged on microscopy. These cells are characterised by a disproportional increase in the ratio of surface membrane area to volume. This gives the cells decreased osmotic fragility, as it allows it to take up more water for a given amount of osmotic stress.
Target cells are most commonly seen in the following clinical conditions :
- liver disease
- haemoglobinopathies
- thalessimia
- post-splenectomy
- iron deficiency
Target cell formation decreases the amount of oxygen that is circulated through the blood and unable to deliver it to all areas of the body. Elevations in target cells are the result of a shift in the exchange equilibrium between the RBC's and the cholesterol.
