Anemia refers to “lack of blood” and implies widespread effects from too little blood volume or blood that is dysfunctional in its oxygen carrying capacity due to whatever type of hemoglobin or erythrocyte problem.
In modern medicine, anemia is diagnosed based on a lowering of hemoglobin concentration below 130 g/l in males and 120 g/l in females whereas too little blood volume is not part of the diagnosis. Most commonly, people with anemia report feelings of weakness, fatigue, or exercise intolerance but also other symptoms may manifest.
Global anemia prevalence in 2010 was 32.9% and accounted for 8.8% of the total disability from all conditions. Prevalence in females was higher in most regions and age groups.
Depending on the disease pathology, anemia may be the result of impaired production of red blood cells, increased destruction of red blood cells (hemolytic anemia) or augmented plasma volume (hypervolemic/ dilutional anemia) – or any combination thereof.
Impaired production of red blood cells may be the results of:
- Iron deficiency anemia, resulting in deficient heme synthesis. Iron deficiency anemia is the most common etiology globally.
- Anemia due to insufficient production of the hormone erythropoietin.
- Thalassemia’s which are genetic disorders inherited from a person’s parents causing deficient globin synthesis.
Increased destruction of red blood cells may be caused by:
- Intrinsic blood cell abnormalities cause premature destruction. Most of these are hereditary genetic disorders.
- Sickle cell anemia results in an abnormality in the oxygen carrying protein haemoglobin and causes early destruction.
Anemia caused by enhanced plasma volume is also referred to as “pseudo anemia” since the total number of red blood cells is unaffected.
- Kidney failure leading to sodium and water retention and thereby to a fluid shift into the blood circulation. This may also be seen with heart failure.
- During pregnancy hormonal changes cause an increase in the mother’s blood volume due to a greater increase in plasma volume than in red blood cell volume. Thus, despite red blood cell volume is increased the mother will appear anemic.