What does abnormal red blood cell morphology mean?

Shape or size is off: Morphology refers to what the red cells look like under the microscope. Changes in size or shape of red cells can give a clue about underlying disease. For example, in iron deficiency, RBCs are small and pale. B12 deficiency they are large in size. Different changes can show liver disease, kidney disease or a bleeding disorder. Changes are most useful in diagnosing anemia (low RBC count).

Many possibilities: RBC morphology is the appearance of the red cells under the microscope. The are numerous abnormalities that can occur in different types of illness. Some of these may be due to a primary blood disorder such as sickle cell anemia. Others may be due abnormalities such as iron deficiency. Others may occur as a result of other diseases such as kidney failure. Some are of no consequence.