What Causes Low Hematocrit

Anemia is a condition in which the level of hemoglobin is low. Low level causes low red blood cells in the blood. Which in turn causes hematocrit. The range of reference varies slightly from the one source to other. But the appropriate range is 13.5 per gram in men and 12 g in women. Hematocrit is the measurement of red blood cells in the blood.

Hematocrit makes it very easy to determine whether the red blood cell is low, high or moderate. This give an idea about the body status and related diseases linked with the condition. Hematocrit is a common blood test that is used to determine the red blood cells percentage in the plasma. It is also called as ai???critai???, ai???Hctai??? or PCV (packed cell volume). Read to know more about anemia, low hematocrit causes and hematocrit test.


Anemia occurs when there is a drop in the red blood cells count. RBCs consist of iron rich proteins called as hemoglobin which are found in the blood. Hemoglobin carries oxygen to all the cells and the tissues. Hemoglobin combines with oxygen to form oxyhemoglobin.

This is the only way in which oxygen is passed to smallest parts of the body. If a person is anemic, he/she may feel tired very soon or fatigue due to less proportion of oxygen in the blood flowing through the body. A person suffering from this can observe symptoms depending on its severity.

What Causes Low Hematocrit

Anemia is caused due to many reasons like hereditary, diseases and abnormalities or bleeding due to some reason. NAAC categories anemia as:

  • Iron deficiency anemia
  • Vitamin deficiency anemia
  • Chronic disease anemia

These factors are considered as the measure target of NAAC. The following is the list of inherited anemia and they are:

  • Thalassemia
  • Sickle cell anemia
  • Fanaconi anemia
  • Diamond blackfan anemia
  • Congenital dyserythropoietic anemia

How is Hematocrit Determined

The process which is useful in determining hematocrite is centrifuging. In this the complete blood is added to a centrifuge tube which is spinned at high speed which separates blood into different parts like RBCs, WBCs and platelets. The amount of RBCs found in the blood is proportion of hematocrit in the blood.

The Process of the Hematocrit Test

Hematocrit is generally measured from a blood sample with the help of an automated machine. These machines mostly do not measure hematocrit directly. The blood sample collected from the patient is added to a device called as centrifuge tube. Hematocrit can also be measured using a centrifuge.

When the blood is centrifuged, highly densed red blood cells get settled at the bottom of the tube.This device spins at a very high speed. Due to which the blood gets separated into different parts such as RBCs, WBCs, platelets, etc. From the proportion of RBCs, the technician determines the level of the hematocrit.

Normal Blood Hematocrit Values

  • Newborn: up to 60%
  • Children: varies with age; One week: 47%-65%; One month: 37%-49%; Three months: 30%-36%; One year: 29%-41%; Ten years: 36%-40%
  • (Adults) Females: 36%-46%; Males: 40%-54%
  • Pregnancy: As the plasma volume increases in the last trimester, there is a decrease in hematocrit levels.

Abnormal results of hematocrit
The following article explains about the reasons for both low and high hematocrit levels.

Reasons for Low Hematocrit

  • Bleeding
  • Leukemia
  • Anemia
  • Red blood cells destruction
  • Over hydration
  • Nutritional deficiencies of folate, vitamin B6, iron and vitamin B12.

Reasons for High Hematocrit

  • Cor pulmonale
  • Erythrocytosis
  • Dehydration
  • Low blood oxygen levels
  • Pulmonary fibrosis
  • Congenital heart disease
  • Polycythemia vera


  • Accumulation of blood under skin
  • Excessive bleeding
  • Infection
  • Feeling light headed or fainting.

Why is the Test Conducted?

Doctors may recommend the test with Complete Blood Picture(CBP). The amount of RBCs found in the test are compared with other blood cells in order to diagnose a disease.

Sample collection

To collect the sample, a needle is pierced into a vein present in the arm in order to draw some blood. You can also use heel stick (for newborns) and finger stick (for adults and children).

Level of Hematocrit Suggests

Low level of hematocrit is an indication if a drop in the white blood cell count than the normal range. This can further result in causeing leukemia, lymphomia, etc. High level of White Blood Cells (WBC) indicate disorders like polycythemia. Low level of hematocrit indicates insufficient supply of red blood cells too.

These results are counted as the percentage of red blood cells found in the blood. In men, the percentage is 38.8 to 50 and in women the percentage is 34.9 to 44.5. The proportion in children varies according to the age and sex. This range is not same with all medical practitioners.

Factors Affecting the Results

  • Pregnancy
  • Recent significant blood loss
  • Recent blood transfusion
  • Living at high altitude severe dehydration

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