Here is the answer to your question.
The dangers of being anemic for too long is that you start having a
lower threshhold for exercise and activity. You are possibly at a
slightly increased risk for infections. Fatigue and irritability creep
in, and the performance of various body organs (like the brain/ heart
etc.) becomes sub-optimal, this is due to a decrease in the oxygen
carrying capacity of the blood, leading to a 'starvation' of the
various organs for oxygen.
Coming to your second question.. when will a blood transfusion be needed?
This is slightly difficult to answer since it depends on a lot of
variables. The general rule of thumb is that ONLY if a patient is
suffering from a hemodynamic compromise (meaning that the heart /
lungs/ Blood pressure) is getting significantly affected, or in a
person who has an underlying pronbelm (like cancer, severe infection,
heart or lung disease) wherein a low hemoglobin can affect the chances
Most otherwise 'healthy' walking people who have a even a VERY LOW
hematocrit (as low as even 15, hb of even 5) may not be given a blood
transfusion without determining the cause.
In an acute injury with blood loss however even an Hb of around 7-8 may
lead to a transfusion since the body has had no time to adjust to the
fall in the hemoglobin. While in a chronic disease (like iron
deficiency, hemolytic anemia, slow blood loss) the body is able to
adjust to much lower values with out the need for a blood transfusion.
The reson why we do not transfuse more frequently is because of the
potential risks of infections that may occur during either their window
period (when tests maybe neggative) or some unknown diseases that we
may not yet be aware of.
So that is the answer then...
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