Also Known As: H&H, Hct, Crit, Packed Cell Volume (PCV), Hb, Hgb.

What Is Hemoglobin and Hematocrit Test?

Hemoglobin and hematocrit are the two blood tests routinely requested to evaluate hemoglobin and RBCs in your blood. These are usually conducted as a part of CBC or blood CP but can also be ordered separately.

Your blood is made up of red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes) suspended in a liquid called plasma which contains nutrients, clotting factors, and water. Hemoglobin is a protein structure in the RBCs that carries oxygen from the lungs to different body tissues and transfers carbon dioxide back to the lungs for clearance. The measure of these two components is crucial for detecting the cause of symptoms, monitoring the treatment response, or tracking chronic health conditions.

HEMATOCRIT is the total number of RBCs in your blood expressed in percentage. The normal range of Hct for men is 40%-54% and for women is 36%-46%. HCT changes with the change in the number of RBCs in your blood as well as with the change in other components and volume of blood. It is the measure of the viscosity of the blood. A minimum of 38% HCT is required for blood donation.

HEMOGLOBIN is an iron-containing protein found in the RBCs that gives RBCs a characteristic red color. It binds and delivers oxygen throughout the body. The normal range of Hb for men is 14-18mg/dl and for women is 12-16mg/dl. Unlike HCT, it does not change with the change in blood volume.

What Is The Test Used For?

The tests are used to screen, diagnose and monitor the conditions that affect blood and bone marrow. It is also done as a part of blood CP and CBC, including WBC and platelet counts. Any derangement above or below the reference ranges suggests some underline cause. An abnormal decrease in the number of RBCs below the reference range is called anemia, and an increase in RBCs above the reference range is called polycythemia or erythrocytosis.

Signs and symptoms of decreased Hb and Hct are:

• Fatigue
• Shortness of breath
• Dizziness
• Headache
• Cold hands and feet
• Fast irregular heartbeats
• Pale and yellow skin

Signs and symptoms of increased Hb and Hct are:

• Weakness
• Flushing of skin
• Itching after shower or bath
• Difficulty in breathing
• Headache
• Sweating
• Bleeding from nose
• Easy bruising
• Painful swelling of joints
• Vision problems
• Enlarged spleen
• Abnormal weight-loss

Why And When Do You Need To Get Tested?

These tests are simple and quick, which help in the rapid evaluation of blood conditions. Your healthcare provider may request these tests:

• As a part of your routine investigations.
• If you are facing any of the above-mentioned signs and symptoms.
• If you are pregnant.
• If you are a patient with a known chronic health condition.
• If you are going for blood donation.
• If you are experiencing acute or chronic blood loss.
• For monitoring the response and side effects of treatment.

What Kind Of Sample Is Required?

A blood sample is drawn by your healthcare provider from the veins of your arm or hand with the help of a small needle which is then transferred into a test tube or vial and transported to the laboratory.

Do You Need To Prepare For The Test?

These tests do not require any special preparation; however, you should inform your healthcare provider about all the medications you have taken recently as they may become a cause of deranged results.

Is There Any Risk To This Test?

You may have very few risks concerned with this test. Watch out for temporary lightheadedness, dizziness, mild bruising, and pain at the site of the prick; very rarely, bleeding or infection may occur. Most of these symptoms go away quickly.

What Does The Test Result Mean?

The results are usually obtained within 12-24 hours and are reported as high or lower than the reference range. There are multiple causes of abnormal results. Deranged levels suggest that your blood is either too thin or thick as compared to other average people of a similar population. Your healthcare provider may correlate your history of symptoms and clinical examination with the test results and concludes the possible cause of derangement. Although hematocrit is measured as a percentage, laboratory reports may not include a % symbol.

Low levels of hemoglobin and hematocrit may be caused by:

• Decrease production of RBCs due to nutritional deficiency of iron (iron deficiency anemia), vitamin B12 and B6 (megaloblastic anemia), Bone marrow suppression (Aplastic Anemia), or chronic kidney disease (due to deficiency of erythropoietin).
• Acute or chronic blood loss or destruction of RBCs due to autoimmune hemolysis or infections like malaria and dengue.
• Certain medicines cause anemia, including cephalosporins, dapsone, levodopa, methyldopa, and chemotherapeutic drugs.
• Hgb can be low during pregnancy due to iron deficiency and HCT due to an increase in plasma volume during pregnancy.
• Excessive water intake may also decrease hematocrit due to increased plasma volume.
• Sickle cell anemia and thalassemia also present with low levels of hemoglobin and HCT.

High levels of hemoglobin and hematocrit can be caused by:

• Overproduction of RBCs due to illness, heart failure, and cancers.
• As a compensatory response to low oxygen caused by high altitude or chronic lung disease (COPD).
• Smoking.
• Dehydration makes Hgb and Hct seem higher than they are due to a decrease in plasma volume.
• Polycythemia vera: a type of blood cancer in which bone marrow produces too many RBCs.

Your healthcare provider may order some other specific tests for further evaluation and determining the cause of illness. If you have any queries related to your test result, you should ask your healthcare practitioner.

Related Tests

• Reticulocyte count
• Coombs test for hemolysis
• Total leukocyte count
• Serum Iron profile
• Hb electrophoresis