Iron Deficiency Anemia: This is the most common cause of microcytic, hypochromic anemia, characterized by low hemoglobin, low Mean Corpuscular Volume (MCV), low Mean Corpuscular Hemoglobin (MCH), and a high Red Cell Distribution Width (RDW) indicating a significant variation in red blood cell size. The high RDW is particularly suggestive of iron deficiency anemia as it reflects the presence of both microcytic and normocytic red cells.

Thalassemia: These are genetic disorders affecting hemoglobin synthesis, leading to microcytic, hypochromic anemia. While they typically present with a low RDW due to uniform small cell size, some forms like thalassemia trait can have a slightly elevated RDW. However, the MCV is usually very low, and other specific tests are needed for diagnosis.
Anemia of Chronic Disease: This can present with similar laboratory findings, especially if there's an underlying chronic inflammatory condition. The anemia is often normocytic but can be microcytic, and the RDW can be elevated, reflecting a mixed population of red cells.
Sideroblastic Anemia: A group of disorders characterized by the presence of ringed sideroblasts in the bone marrow. They can present with microcytic, hypochromic anemia and an elevated RDW. This condition can be congenital or acquired, often related to drugs, toxins, or myelodysplastic syndromes.

Celiac Disease: An autoimmune disorder that can lead to iron deficiency anemia due to malabsorption. It's crucial to consider this diagnosis, especially in patients with gastrointestinal symptoms or a family history of the disease.
Chronic Blood Loss: Any source of chronic blood loss (e.g., gastrointestinal bleeding, menstrual disorders) can lead to iron deficiency anemia. Identifying and treating the underlying cause is critical.
Myelodysplastic Syndromes (MDS): A group of disorders caused by poorly formed or dysfunctional blood cells. MDS can present with a variety of anemia types, including microcytic, hypochromic anemia with an elevated RDW. This diagnosis is particularly important in older adults or those with a history of exposure to certain chemicals or radiation.

Porphyrias: A group of disorders that result from defects in heme biosynthesis. Some porphyrias can present with microcytic, hypochromic anemia, though this is less common.
Lead Poisoning: Can cause microcytic, hypochromic anemia due to its effect on heme synthesis. The RDW might be elevated, and basophilic stippling may be seen on the blood smear.
Copper Deficiency: Though rare, copper deficiency can lead to microcytic, hypochromic anemia. It's often associated with neurological symptoms and is more commonly seen in patients with malabsorption or those receiving total parenteral nutrition without adequate copper supplementation.