Which condition is characterized by Vitamin B12 deficiency due to absorption issues?

Pernicious anemia is specifically characterized by a deficiency of vitamin B12 that occurs due to absorption issues in the gastrointestinal tract. This condition is primarily caused by the lack of intrinsic factor, a protein required for the intestinal absorption of vitamin B12. Intrinsic factor is produced by the stomach lining, and its absence (often due to autoimmune destruction of these cells) leads to inadequate absorption of vitamin B12, resulting in symptoms such as anemia, fatigue, neurological changes, and gastrointestinal issues.

The other anemia types listed are not related to vitamin B12 absorption. Hypochromic anemia is typically associated with iron deficiency, where the body has insufficient iron to produce healthy red blood cells. Iron deficiency anemia results from a lack of iron intake, loss, or absorption issues, quite distinct from vitamin B12 deficiencies. Sideroblastic anemia involves problems with incorporating iron into hemoglobin and is linked to defective erythropoiesis or metabolism of iron, rather than absorption of vitamin B12 specifically.