RBC indices |
| Definition: |
| A part of the complete blood count (CBC) test that includes the average red blood cell size (MCV), hemoglobin amount per red blood cell (MCH), and hemoglobin concentration (hemoglobin amount relative to the size of the cell) per red blood cell (MCHC); MCH and MCHC are calculated from other CBC measurements (see also RBC count). Red blood cells transport hemoglobin which, in turn, transports oxygen. The amount of oxygen received by tissue is dependent on the amount and function of RBCs and hemoglobin. The MCV, MCH, and MCHC reflect the size and hemoglobin content of individual red blood cells. |
| Alternative Names: |
| Erythrocyte indices; Blood indices; Red cell mass measurement; MCH (mean corpuscular hemoglobin); MCHC (mean corpuscular hemoglobin concentration); MCV (mean corpuscular volume) |
| How the test is performed: |
| Adult or child: Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding. Infant or young child: The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding. The values for MCHC, and MCH are derived from the hemoglobin (Hgb), hematocrit (Hct) and red blood cell count (RBC) by mathematical calculations:
The MCV is measured directly. |
| How to prepare for the test: |
| Adults: No special preparation is necessary. Infants and children: The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
|
| How the test will feel: |
| When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing. |
| Why the test is performed: |
| MCV values reflect the size, and MCH and MCHC reflect the hemoglobin concentration of individual cells. These RBC indices are useful in the differential diagnosis of types of anemia. Anemias are classified on the basis of cell size (MCV) and amount of Hgb (MCH).
|
| Normal Values: |
| MCV: 80 to 100 femtoliter MCH: 27 to 31 picograms/cell MCHC: 32 to 36 grams/deciliter |
| What abnormal results mean: |
| Anemias have been classified as follows: normocytic/normochromic (NC/NC) anemia:
|
| What the risks are: |
| Special considerations: |
| Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others. |
Reviewed By: Rebecca Elstrom, M.D., Division of Hematology-Oncology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.
 |
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch). |
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2003 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
