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Blood Volume Blood Test

Last updated June 14, 2018

Approved by: Krish Tangella MD, MBA, FCAP

The Blood Volume Blood Test helps determine the volumes of total blood, plasma, and red blood cells. It is used to diagnose various blood disorders and monitor bleeding.

What are other Names for this Test? (Equivalent Terms)

  • Red Blood Cell Volume Blood Test
  • Serum Volume Blood Test
  • Total Blood Volume Blood Test

What is Blood Volume Blood Test? (Background Information)

  • Blood is made up of plasma (46-63%) and formed elements (37-54%)
    • Plasma is the fluid portion of blood. It contains proteins (7%), other solutes (1%), and water (92%). Albumin, made in the liver, is the most abundant protein in blood
    • Formed elements are cells and cellular fragments. The vast majority of these are red blood cells (99.9%, 25 trillion or so). The rest are white blood cells and platelets. Blood volume comprising formed elements is called hematocrit
  • Serum is a term that refers to the liquid left after blood has clotted. It contains the same elements as plasma, except that it lacks fibrinogen, a protein that eventually forms the blood clots
  • The Blood Volume Blood Test helps determine the volumes of total blood, plasma, and red blood cells. It is used to diagnose various blood disorders and monitor bleeding
  • The test combines sample blood with radioactive substances to allow for detection. Cr-51-tagged red cells are used to measure red blood cell volume and I-131- or I-125-tagged albumin for plasma volume

What are the Clinical Indications for performing the Blood Volume Blood Test?

Following are the clinical indications for performing the Blood Volume Blood Test:

  • Monitoring blood loss during surgery
  • Monitoring bleeding, particularly to the GI tract and uterus
  • Determining the major blood component that is lost, prior to replacement therapy
  • Abnormal heartbeat
  • Abnormal blood pressure
  • Dizziness
  • Fatigue
  • Trouble breathing

How is the Specimen Collected for Blood Volume Blood Test?

Following is the specimen collection process for Blood Volume Time Blood Test:

Sample required: Blood

Process of obtaining blood sample in adults:

  • A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
  • The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
  • The needle cap is removed and is held in line with the vein, pulling the skin tight
  • With a small and quick thrust, the vein is penetrated using the needle
  • The required amount of blood sample is collected by pulling the plunger of the syringe out slowly
  • The wrap band is removed, gauze is placed on the collection site, and the needle is removed
  • The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
  • The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal

Preparation required: No special preparation is needed prior to the test.

What is the Significance of the Blood Volume Blood Test Result?

Following is the significance of the Blood Volume Time Blood Test:

  • A high value for the test may indicate:
    • Dehydration (red blood cell volume)
    • Polycythemia vera
    • Overhydration (total volume)
  • A low value for the test may indicate:
    • Dehydration (total and plasma volume)
    • Hypovolemic shock
    • Hemorrhaging

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Certain factors, such as diet and hydration status, can interfere with the Blood Volume Blood Test

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

The following DoveMed website links are useful resources for additional information:



Please visit our Laboratory Procedures Center for more physician-approved health information:


References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Jan. 26, 2016
Last updated: June 14, 2018