Anemia is defined as decreased or poor maturation of red blood cells (RBC) and there are multiple etiologies for developing anemia. The most common cause is due to an iron deficiency.
If a person with iron deficiency has their blood looked at under a microscope in a lab, the report will be that the RBC will be hypochromic microcytic.
- Hypo=small, chromic = color. That means the color is not red but a very pale pink.
- Micro=small, cytic=cell. The size of the cell is smaller than normal.
- So a person with iron deficiency anemia has a pale and small RBC.
There will be a low count of RBC’s and decreased hemoglobin. This will cause a decreased amount of oxygen to be circulating throughout the body and the heart will be put under greater stress trying to circulate the blood. The heart will have to pump faster in severe anemia, to the point of high-output-failure occurring in an otherwise healthy heart!
Etiology
The most common cause of iron deficiency anemia is due to blood loss which could be due to an injury or a woman’s menses. In most instances it’s not a large amount of blood loss during the menstrual cycle, but in some individuals they can have a heavy flow. The body will replace blood but you have to have an adequate amount of iron to help replace the hemoglobin to make normal RBC.
Another reason for iron deficiency is not enough iron in a persons diet or a lack of absorption.
Recap
- Hypochromic microcytic anemia
- Decreased RBC’s and decreased hemoglobin
- Decreased oxygen binding
- Can cause high output cardiac failure
- Etiology
- Blood loss
- Inadequate diet or absorption
Iron Replacement
Orally
We can replace iron orally but this therapy can take up to 6 months. We could calculate how low a person is in terms of iron deficiency. A person with very severe anemia may be short of up to two grams of iron in their body. The two common place we have iron are the bones, and a little bit in the liver and spleen.
The most common iron tablets are 325mg tablets. They can’t just take 7 tablets and be cured. The most common iron tablets are not pure iron but iron sulfate (FeSO4). There’s also iron gluconate, iron fumarate, and so forth but iron sulfate has the most amount of iron (and it’s the most constipating).
In these 325mg FeSO4 tablets, only 65mg of Fe exists. We can’t take 30 tablets of this and be cured because the body is going to absorb, at best, only 10% of this dosage. That means at best, only 6.5mg of iron will be absorbed. When you are the most deficient of iron, your body will absorb the most it can and absorb up to 6.5mg at most. As a person gets more and more iron in the blood, the body will absorb less and less of it. Instead of 10%, the body may absorb only 1% of the iron after a few weeks. That’s just 0.65mg Fe!
Eventually, after 4-6 weeks, the blood levels will look more normal but to replenish the storage areas, it may take 6 months or more because they’re absorbing less than 1mg per dose. If we had to replace it faster, we can give them injections.
Intramuscular
In the deep muscle we can do a z-track administration (otherwise iron injections will stain). The maximum volume that you can inject intramuscularly is 2-3ml. We could give a person up to 100mg of iron a day if they have severe anemia. To replace 2 grams of iron (in the case of severe anemia), it would take three weeks (20 injections) of daily, painful, deep IM injections to get them back to normal.
Intravenous
What color is iron? Black. It doesn’t look right to the patient because a black bag of liquid will be hanging from their IV. The manufacturers guidelines say you can’t give more than 100mg of iron a day intravenously either. So this would again require 20 days of treatment. There are rare situations when we have to move faster than 3 weeks and we will give larger doses (such as for pregnancy).
Patient Complaints
Constipation: The main complaint from patients are constipation. We can give them laxatives, a different salt form of iron and there’s also a slow-release iron. Slow Fe, slow release iron, may be less constipating. So those are your few options.
Stool color: Patients stool will turn a black color because you absorbed, at best, 10% of the dose and the 90% of the dose goes straight out with the stool.
Recap for Iron Replacement
- Oral Therapy
- Replacement therapy may require 6 months
- IM
- Z-track administration
- Limited daily volume
- IV
- Guidelines limit use to 100mg per day
- Required for quick iron replacement (pregnancy, ulcerative colitis)
