Final answer:
The most common causes of anemia categorized by cell size include vitamin deficiencies (B12, folate) for macrocytic anemia, chronic diseases for normocytic anemia, and iron deficiency for microcytic anemia. Conditions like Crohn's disease, autoimmune disorders, thalassemia, and environmental exposures can also contribute.
Step-by-step explanation:
The most common causes of macrocytic, normocytic, and microcytic anemia are based on issues related to red blood cell (RBC) production, destruction, or loss. These can be categorized through kinetic and morphological approaches, analyzing aspects like the size of RBCs using mean corpuscle volume (MCV) tests and reticulocyte counts.
Macrocytic Anemia
In the case of macrocytic anemia, a common cause is vitamin deficiency, notably of vitamin B12 and folate. Circumstances resulting from diet deficiencies, the inability to absorb these vitamins, or conditions like Crohn's disease could contribute. Megaloblastic anemia is a type of macrocytic anemia primarily due to vitamin B12 and folate shortage.
Normocytic Anemia
For normocytic anemia, the causes are often due to diseases that affect the production of RBCs, such as chronic kidney diseases, certain cancers, or autoimmune conditions like lupus and rheumatoid arthritis.
Microcytic Anemia
Microcytic anemia is typically caused by iron deficiency, which can arise from a diet low in iron, poor absorption, or chronic bleeding. Other factors include hereditary conditions like thalassemia or environmental exposures like lead which can impair RBC production.