The average quantities of blood are::
about 9 pints (4.3 liters) of blood in an average-sized female (5 feet 5 inches tall and weighing 165 pounds)about 12.2 pints (5.7 l) in an average-sized male (6 feet in height and weighing 200 pounds)in an infant, about 1.2 fluid ounces (fl oz) for every pound of body weight (75 – 80 milliliters (ml) of blood per kilogram).in a child, about 1–1.2 fl oz for every pound of body weight (70–75 ml of blood per kg)
For clarity, Medical News Today has converted these figures from the formula given in Open Anesthesia.
Blood volume test
According to an older article in the Journal of Nuclear Medicine Technology, a blood volume test can measure the amount of blood in a person’s body.
A doctor may use this test to assess a variety of conditions, such as:
congestive heart failurekidney failureshock
There are different ways of testing, but a blood volume test usually involves injecting a small amount of a tracer substance into the body. A healthcare professional will then use imaging technology to track blood moving around the body.
How much blood can you lose or donate?
According to the American Red Cross, the standard amount of blood a person will give during a blood donation is 1 pint. This is around 10% of the blood in the body and a safe amount of blood to lose.
A person may feel a little faint after donating blood, and so donation centers ask donors to rest for 10–15 minutes and take some refreshments before leaving.
If a person has an illness or accident, they may lose more blood. This can lead to shock, and it can be life threatening.
Donating blood can save lives, but how does it affect the donor?
Shock and blood loss
Severe bleeding can be dangerous. In medical terms, shock means that not enough oxygen is reaching tissues in the body. Low oxygen levels can cause damage to the brain and other organs.
If someone is losing blood, the body will start to direct blood toward the vital organs and away from the skin, fingers, and toes. A person may begin to look pale or feel numbness in their extremities.
Excerpt
Blood volume refers to the total amount of fluid circulating within the arteries, capillaries, veins, venules, and chambers of the heart at any time. The components that add volume to blood include red blood cells (erythrocytes), white blood cells (leukocytes), platelets, and plasma. Plasma accounts for about 60% of total blood volume, while erythrocytes make up roughly 40%, along with leukocytes and platelets. The amount of blood circulating within an individual depends on their size and weight, but the average human adult has nearly 5 liters of circulating blood. Women tend to have a lower blood volume than men. However, a woman's blood volume increases by roughly 50% during pregnancy.
Blood volume is tightly regulated and related to multiple organ systems. Furthermore, it is closely associated with sodium content and hydration status. The maintenance of blood volume is crucial to normal function as it is necessary for the constant perfusion of body tissues. Blood volume can be increased or decreased by systemic dysfunction. Changes in blood volume can result in various clinical scenarios such as hypovolemic shock or edema.
Two equations exist for estimating blood volume given the gender, height (H), and weight (W) of the patient. The Nadler equation is built upon the work of Dr. Allen in 1962, while the Lemmens-Bernstein-Brodsky equation is more accurate for higher ranges of body weight and body mass indices in patients without critical illnesses.
Nadler Equation :
Men: Blood Volume = (0.3669 × H^3) + (0.03219 × W) + 0.6041
Women: Blood Volume = (0.3561 × H^3) + (0.03308 × W) +0.1833
Lemmens-Bernstein-Brodsky Equation :
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