Transcript
Lecture 7
Erythrocyte Indices
Important in assessing border-line of anemia Should Should be interpreted only in the light of otherfindings otherfindings i.e. appearanc appearancee or RBCs RBCs on fixed smears Computed using: RBC count, Hemoglobin (Hgb), and haematocrit (Hct)
Types of RBC Indices 1. Mean Corpuscular Volume (MCV) 2. Mean Corpuscular Hemoglobin (MCH) 3. Mean Corpuscular Hemoglobin Concentration 4. 5. 6. 7. 8.
(MCHC) Color Index (CI) Volume Index (VI) Saturation Index (SI) Mean corpuscular Diameter (MCD) Mean Corpuscular Thickness (MCAT)
1. MCV (Mean corpuscular volume) – average volume of individual blood cell
Volume % Hct = ---------------------- X10 = cubic micra or femtoliter RBC in million = NV = 82 -92 cubic micra (u3) Interpretation: 95 – 160 u3 = macrocytic anemia 72 – 79 u3 = microcytic anemia 50 – 71 u3 = microcytic, hypochromic
Example:
Given: Hct = 46 vol%; RBC count = 5,000,000 / mm 3 46 MCV = --------- X 10 = 92 mm3 5
NV = 82 -92 cubic micra (u3)
Normocytic
2. MCH (Mean Corpuscular Hemoglobin) =ratio of hgb to red cell count =average weight or amount of Hgb in an individual RBC Gm Hgb = ------------- X 10 = micromicrogram (uug) or*picogram RBC in Million *pictogram = millionth part of microgram or gram x 10 -12 Normal Value: 27 – 33 uug or pg Interpretation: >33 uug = macrocyte <27 uug = microcyte <22 uug = microcytic hypochromic
2. MCH (Mean Corpuscular Hemoglobin) Example: Given: Hgb = 16 gm/100 ml; RBC count = 5,500,000/mm3
Gm Hgb MCH = ------------- X 10 RBC in Million 16 MCH = --------- x 10 = 29 uug 5.5 Normochromic
Normal Value: 27 – 33 uug or pg
3. Mean Corpuscular hemoglobin Concentration (MCHC) =mean concentration of Hgb in the average RBC Gm Hgb MCHC = ------------- X 100 = % Vol % Hct
Normal Value = 32 – 38%
Example: Given: Hgb = 16gm/100 ml; Hct = 46 vol% 16 MCHC = ------- X 100 = 34.7% 46
** MCH measures the weight of Hgb in the average red cell and is reported in uug or pictogram; Whereas, MCHC indicates concentration of Hgb in the average red cell reported in %.
Use of Erythrocyte Indices: The MCV, MCH, MCHC are called red cell indices, gives accurate picture of RBC morphology in fixed smears
Example1: Given: RBC = 4.5 mil/mm3, Hgb = 13.5 gm/100ml; Hct = 40 vol% 40 MCV = ------- X 10 = 89 cubic micra 4.5 13.5 MCH = ----- X 10 = 30 uug 4.5 13.5
MCHC = ------ X 100 = 33.8% 40
Normal Value: MCV= 82 -92 cubic micra (u3) MCH= 27 – 33 uug or pg MCHC = 32 – 38%
Therefore, the RBCs are normal in size (normocytic); the hgb concentration is normal (normochromic)
Example 2:
Describe the cell size, hemoglobin weight and hemoglobin concentration.
Given: MCV = 89 cubic micra, MCH = 25.5 uug; MCHC = 28.8 % Normal Value: MCV= 82 -92 cubic micra (u3) MCH= 27 – 33 uug or pg MCHC = 32 – 38%
Describe the cell size, hemoglobin weight and hemoglobin concentration.
Given: MCV = 89 cubic micra, MCH = 25.5 uug; MCHC = 28.8 %
Therefore, RBCs are normal in size or Normocytic, but contain less hgb than normal; Low MCHC shows to be hypochromic.
Example 3: Given: MCV = 71 cubic micra; MCH = 22.2 uug; MCHC = 31.2%
Normal Value:
MCV= 82 -92 cubic micra (u3) MCH= 27 – 33 uug or pg MCHC = 32 – 38%
Describe the cell size, hemoglobin weight and hemoglobin concentration.
Other Blood Indices: 1. COLOR INDEX (C.I.) = average amount of haemoglobin in each erythrocyte as compared with the average amount in a normal erythrocyte
% hemoglobin CI = ------------------------------% RBC
Example: RBC = 3, 200,000/mm3; Hgb = 9.6 gm/100 ml % hemoglobin So: CI = ------------------------% RBC Given Hgb (9.6) % Hgb = ---------------------------- X 100 = 60% Standard Hgb (16) Given RBC Ct (3,200,000) % RBC = --------------------------------Standard RBC ct. (5,000,000) Therefore: 60 Color Index = ----------- = 0.94 64 Normal Value: 0.90 to 1.10
X 100 = 64%
COLOR INDEX (C.I.)
Note: Increased in pernicious anemia due to macrocytes and megalocytes
Decreased in secondary anemia and chlorosis
2. VOLUME INDEX (V.I.) = average size of RBC as compared with the average size of a normal RBC Percent Hct (% Hct) V.I. = ------------------------------Percent RBC (%RBC)
Example: RBC count= 3,000,000/mm 3; Hct = 32 vol% So: Percent Hct (% Hct) V.I. = ------------------------------Percent RBC (%RBC)
Given Hct (32) % Hct = --------------------------- X 100 = 68% Standard Hct (47) Given RBC c t. (3,000,000) %RBC = ------------------------------------- X 100 = 60% Standard RBC (5,000,000) Therefore: 68 Volume Index = ------- = 1.13 60
Normal Value: 0.90 – 1.10
2. VOLUME INDEX (V.I.)
Note: Increased in infants during the first few weeks of life, Decreased in older children, usually lower than adult
3. SATURATION INDEX (S.I.)
= average amount of haemoglobin per unit volume of cell in relation to the normal Color index %Hgb S.I. = --------------------- or ------------ Volume Index % Hct
Example: RBC ct. = 3,500,000/ mm3 (3.5/5) = 70% Hgb = 12gm/100ml (12/16)= 75% Hct = 31vol% (31/47) = 66% Color index S.I. = -------------------- Volume Index
%Hgb or ------------% Hct
75 Color Index = ------- = 1.07 70 66 Volume Index = ------ = 0.94 70
3. SATURATION INDEX (S.I.) Therefore: 1.07 Saturation Index = --------- = 1.14 0.94 Or:
75 Saturation Index = ------- = 1.14 66
Normal value: 0.80 to 1.20
4. MEAN CORPUSCULAR DIAMETER (MCD) = mean or average diameter of the rbc in terms of micron
5. MEAN CORPUSCULAR AVERAGE THICKNESS (MCAT) = mean or average thickness of rbc MCV MCAT in micron = -----------(MCD)2 _________
2 **The thickness is obtained by dividing the MCAT by the normal MCAT
Thank You
