Hematocrit

Also known as Packed Cell Volume

This test is for

Male, Female

Test Preparation

No special preparation required

Understanding Hematocrit

What is Hematocrit?

Packed Cell Volume (PCV), also known as hematocrit test, is performed to measure the proportion of blood made up of erythrocytes or red blood cells (RBCs). Human blood is made up of RBCs, white blood cells (WBCs) or leukocytes and platelets which are suspended in a fluid called plasma.

This test helps you to diagnose and determine the severity of conditions causing anemia or polycythemia. Lower than normal pcv value indicates low amount of RBCs in circulation (indicating anemia) whereas higher than normal pcv indicates high amount of RBCs in circulation (indicating polycythemia).

It also helps to monitor treatment efficacy for anemia or polycythemia, determine if blood transfusion is necessary and assess dehydration. It also forms a vital part of Complete Blood Count (CBC) Test in regular health checkups.

What is Hematocrit used for?

The Packed Cell Volume Test is performed:

· As a part of Complete Blood Count (CBC) Test in regular health checkups

· To diagnose and determine the severity of conditions causing anemia (lower than normal RBC, hemoglobin, or hematocrit), or polycythemia (higher than normal RBC, hemoglobin, or hematocrit)

· To monitor treatment efficacy for anemia or polycythemia

· To determine if blood transfusion is necessary

· To assess dehydration

What does Hematocrit measure?

Human blood is made up of erythrocytes or red blood cells, leukocytes or white blood cells, and platelets suspended in a fluid called plasma. Each of the component of blood performs a specific function. The packed cell volume or hematocrit is a ratio of the volume occupied by the RBCs to the total volume occupied by all the blood components or whole blood.

The RBCs transport inhaled oxygen from the lungs to all the cells of the body, and also a small amount of carbon dioxide from the cells to the lungs to be exhaled. The majority of carbon dioxide is transported in solution in plasma as bicarbonate ions. They contain a protein called hemoglobin which binds to oxygen for transport.

RBCs are produced in the erythropoietic cells of the bone marrow in response to the hormone Erythropoietin secreted by the kidneys when oxygen saturation of blood is detected to be low (hypoxia). The average lifespan of RBCs in circulation is 120 days. Hence, the bone marrows continuously produce RBCs to maintain a steady concentration in blood. The Packed Cell Volume Test depends on the count as well as the average size of the RBCs (Mean Corpuscular Volume or MCV). Higher than normal amount of RBCs produced by the bone marrow can cause the hematocrit to increase, leading to increased blood density and slow blood flow. Lower than normal hematocrit can be caused by low production of RBCs, reduced lifespan of RBC in circulation, or excessive bleeding, leading to reduced amount of oxygen reaching the cells.

Interpreting Hematocrit results

Interpretations

Adult male	40-50%
Adult female	36-46%

Note: Normal range of Hematocrit depends on a number of factors apart from age, including gender, health condition, previous instance of diseases, etc. The range also varies slightly between different laboratories performing the test.

Lower than normal packed cell volume for RBCs indicates low amount of RBCs in circulation and causes anemia.

Higher than normal packed cell volume for RBCs indicates high amount of RBCs in circulation and causes polycythemia.

Hematocrit Test results are to be interpreted with the results of other tests including blood iron tests, RBC count, and hemoglobin tests while evaluating anemia.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Hematocrit

Frequently Asked Questions about Hematocrit

Q. Is there any risk associated with the Packed Cell Volume Test?

There is no risk associated with the test. However, since this test involves a needle prick to withdraw the blood sample, in rare cases, a patient may experience excessive bleeding, hematoma formation (blood collection under the skin), bruising or infection at the site of needle prick.

Q. What other tests can be prescribed by your doctor in case the results of Packed Cell Volume Test are not normal?

Other tests that may be prescribed upon appearance of an abnormal result in the Packed Cell Volume Test include: · Complete Blood Count (CBC) Test · Blood Iron Tests (TIBC, UIBC, Hemoglobin) · Reticulocyte Count Test · Blood Smear Test · Vitamin B12 Deficiency tests · Biopsy

Q. What factors can give rise to a high hematocrit?

High hematocrit value may be an indication of higher than normal number of RBCs in circulation. This may occur due to: · Dehydration, which reduces whole blood volume, resulting in artificially high hematocrit · Lung diseases cause increased RBC production due to reduction in oxygen intake · Congenital heart diseases · Kidney tumor that increases erythropoietin secretion · Smoking cigarettes · Living at high altitudes · Genetic conditions causing reduced oxygen sensitivity, reduced oxygen carrying capacity of hemoglobin · Polycythemia vera, a rare disease in which excess RBCs are produced in the bone marrow

Q. What factors can affect hematocrit values?

Hematocrit values of blood can be affected by a number of factors, including: · Living at high altitudes · Pregnancy · Recent large-scale blood loss · Recent transfusion of blood · Severe dehydration

+ more