Leukopenia and neutropenia
Both neutropenia and leukopenia terms may be used instead of each other, and this is largely not false. Neutrophils form the majority of white blood cells and a fall of neutrophils will almost certainly cause a fall in the total number of white blood cells, however if the number of neutrophils falls alone, it might be a different diagnosis, and is therefore important for doctors to check what is called a differential count of white blood cells to see what type of white blood cells fell in number.