Erythrocyte indices: Difference between revisions
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imported>Howard C. Berkowitz |
imported>Howard C. Berkowitz |
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Also commonly called '''red blood cell indices''' or '''RBC indices''', the '''erythrocyte indices''' are a set of clinically useful parameters calculated from measurements of [[erythrocyte]]s. These are commonly reported as part of a [[complete blood count]]. | Also commonly called '''red blood cell indices''' or '''RBC indices''', the '''erythrocyte indices''' are a set of clinically useful parameters calculated from measurements of [[erythrocyte]]s. These are commonly reported as part of a [[complete blood count]]. | ||
==Basic indices== | ==Basic indices== | ||
These are computed from the three basic measurements on erythrocytes: | |||
*Hemoglobin (Hgb), in grams per 100ml | |||
*Hematocrit (Hct), a percentage | |||
*Red blood cell count (RBC), millions per cubic micrometer | |||
===Mean corpuscular volume=== | ===Mean corpuscular volume=== | ||
Usually called MCV, this is the average volume enclosed by a red cell, calculated as: | Usually called MCV, this is the average volume enclosed by a red cell, calculated as: | ||
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===Mean corpuscular hemoglobin=== | ===Mean corpuscular hemoglobin=== | ||
MCH = (Hgb * 10)/RBC | MCH = (Hgb * 10)/RBC | ||
===Mean corpuscular hemoglobin concentration=== | ===Mean corpuscular hemoglobin concentration=== | ||
MCHC = (Hgb * 100) / Hct | MCHC = (Hgb * 100) / Hct | ||
Classification: | |||
*Hypochromic: < 32 | |||
*Normochromic: 32-36 | |||
*Hyperchromic: > 36 | |||
==Additional derivations== | ==Additional derivations== | ||
Revision as of 18:34, 8 December 2009
Also commonly called red blood cell indices or RBC indices, the erythrocyte indices are a set of clinically useful parameters calculated from measurements of erythrocytes. These are commonly reported as part of a complete blood count.
Basic indices
These are computed from the three basic measurements on erythrocytes:
- Hemoglobin (Hgb), in grams per 100ml
- Hematocrit (Hct), a percentage
- Red blood cell count (RBC), millions per cubic micrometer
Mean corpuscular volume
Usually called MCV, this is the average volume enclosed by a red cell, calculated as:
MCV = 10 x (Hematocrit / Red Blood Cell Count)
It is especially useful in the differential diagnosis of anemia. The basic classification of MCV, using approximate values, is:
- <80: Microcytic
- 80-100: Normocytic
- >100: Macrocytic
Exact cutoffs for each range vary with the patient's age and sex, and both laboratory method and expert opinion. For example, a number of hematologists use < 78 as the beginning of the microcytic range.
Mean corpuscular hemoglobin
MCH = (Hgb * 10)/RBC
Mean corpuscular hemoglobin concentration
MCHC = (Hgb * 100) / Hct
Classification:
- Hypochromic: < 32
- Normochromic: 32-36
- Hyperchromic: > 36
Additional derivations
Mentzer index
Mentzer Index = MCV / RBC Count
- Ratio <13: Thalassemia
- Ratio >13: Iron deficiency anemia, Hemoglobinopathy