Blood volume is the amount of blood in a person’s circulatory system. The average adult has at about 4.7 to 5 liters of blood. Generally, women have less blood volume. But during pregnancy blood volume doubles. This is due to increased fluid and white blood cells in the body. Even so, a pregnant women still needs iron supplements to avoid anemia and to properly nourish the developing fetus. Those living in high altitudes have higher blood volume because the air is thin and has less oxygen. The extra blood volume will help provide the body with the needed oxygen. It is also observed that the people in high altitudes have bigger lungs.
The main organ of the body responsible for the maintenance of normal blood volume level is the kidney. When the blood volume increases than normal, the kidney reabsorbs less water and excretes more urine. When the blood volume decreases, the kidney reabsorbs more water and other substances and the urine volume decreases.
There is a standard formula to determine the blood volume. It is BV= PV/1-HC. BV= blood volume, PV= plasma voluma, HC= hematocrit volume. When treating patients with congestive heart failure, chronic hypertension, renal problems and other related diseases blood volume is measured to aid in proper diagnosis and treatment.
Normal blood volume is critical to the over all health of an individual because blood transport oxygen and nutrients throughout the body. Critical blood lost will dangerously lower blood pressure and lead to death.