The two main causes of megaloblastic anemia are either a folic acid or a B12 deficiency.  Another name for a B12 deficiency is cyanocobalamin deficiency.  The most damaging deficiency is the B12 deficiency (known specifically as pernicious anemia) because it can cause nerve damage.  Before nerve damage occurs though, the signs are megaloblastic anemia (the red blood cells look huge).

Replacement with the wrong vitamin can mask the deficiency: If you give a person folic acid, the persons RBCs go back to looking normal.  If they have a B12 deficiency and you give them folic acid, their RBC go back to looking normal as well but the nerve damage is still occurring because they still have a B12 deficiency.

Cyanocobalamin Deficiency

We have plenty of B12 stored in our body, mostly in the bone marrow. If a person stops consuming red meat, it takes about a year for the symptoms to appear:

• Irreversible nerve damage
• Constipation

Poor Diet or Vegetarians: The main cause of cyanocobalamin deficiency is a poor diet. We get B12 from red meat and a vegetarian doesn’t have that so they are prone to B12 deficiency. They need to supplement themselves with B12 cause they’re not going to get it from their normal diet.

Lack of Intrinsic Factor is another reason for B12 deficiency. This is produced in our stomach and it’s to help absorb the B12. Without Intrinsic Factor, we can’t absorb B12. Some individuals can’t produce IF (they may have had stomach surgery or gastritis) and they would have to get a monthly B12 injection for their entire life.

Therapy of B12 deficiency

Replacement Therapy (IM or Subcutaneously) can be done. This will take just three B12 injections for a week. If the individual gets these injections and it turns out that they still have anemia and it’s due to a lack of intrinsic factor, they will receive monthly, 1ml injections of IF for the rest of their life.

Recap

• Cyanocobalamin Deficiency
  • Poor diet (vegetarian)
  • Lack of Intrinsic Factor (produced in stomach)
  • Onset of symptoms takes 1 year
  • Also known as Pernicious Anemia
• Therapy
  • Replacement Therapy
    • Intramuscular or Subcutaneous
  • Those that lack intrinsic factor will receive monthly injections