Other Anemias
A patient's anemia won't resolve with iron supplements — and giving the wrong vitamin could mask a deficiency that permanently destroys the spinal cord. Knowing which anemia is which changes everything.
Core Concept
B12 deficiency, folate deficiency, and aplastic anemia are distinct from iron deficiency anemia in etiology, labs, and nursing priorities. Vitamin B12 (cobalamin) requires intrinsic factor from gastric parietal cells for absorption; deficiency causes megaloblastic anemia with uniquely neurological features — peripheral neuropathy, paresthesias, ataxia, and cognitive changes. Common causes include pernicious anemia (autoimmune destruction of parietal cells), gastrectomy, and strict vegan diets. Treatment is parenteral B12 (IM cyanocobalamin) when intrinsic factor is absent; oral supplementation won't absorb. Folate deficiency also produces megaloblastic anemia with macrocytic RBCs (MCV >100 fL) but lacks the neurological symptoms. Causes include poor dietary intake, alcoholism, and certain drugs (methotrexate, phenytoin). Critically, folate supplementation can correct the hematologic picture of B12 deficiency while the neurological damage silently progresses — this is the dangerous masking effect. Aplastic anemia is bone marrow failure causing pancytopenia — low RBCs, WBCs, and platelets simultaneously. It results from toxins, radiation, certain drugs (chloramphenicol, carbamazepine), or is idiopathic. Nursing care focuses on infection prevention (neutropenia), bleeding precautions (thrombocytopenia), and fatigue management. Definitive treatment is bone marrow transplant or immunosuppressive therapy.
Watch Out For
Don't confuse B12 deficiency with folate deficiency: both are megaloblastic and macrocytic, but only B12 causes neurological damage. Students assume all anemias respond to iron — B12 and folate deficiencies require their specific vitamins, not iron. Aplastic anemia is NOT a nutritional deficiency; it's marrow failure causing pancytopenia, not just low RBCs. The MCV distinguishes macrocytic anemias (>100 fL) from the microcytic picture of iron deficiency (<80 fL).
Clinical Pearl
Neuro symptoms = B12, not folate. Never give folate alone until B12 deficiency is ruled out — you'll fix the blood count while the nerves quietly die.
Test Your Knowledge
3 quick questions — see how well you understood Other Anemias