red cell indices nada mohamed ahmed, md, mt (ascp)i
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Red Cell Indices
Nada Mohamed Ahmed ,MD, MT (ASCP)i
Packed Cell Volume
• PCV(haematocrit) is a portion of blood volume occupied by RBC . PCV is needed to detect anaemia. PCV is tested by :centrifugation & read by a haemotacrit reader,
Measurement of Heamatocrit
1 - Collect blood sample in heparinized
capillary tube
2- Centrifuge
3- Read by heamatocrit reading scale
Hematocrit
• Microhematocrit– Centrifuge– Packed cell column
showing separation of cellular components
Normal value
• Refernce Range For PCV• Males 0.40 - 0.54 L/L• Females 0.35 - 0.47 L/L
Male Female Average
PCV % 40-54 35-47 35-54
Clinical Application
Hct (PCV): RBC (polycythemia) plasma volume (hemo-
concentration)
Hct (PCV): RBC (anemia), plasma volume (hem-dilution)
Sources of Error in PCV Testing:
High or low PCV may be due to:1. faulty reading of result .2. inaccurate tubes.3. wrong anticoagulant amount, causes
cell shrinking & swelling.
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• Calculation Of Red Cell Indices
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RBC Indices
RBC indices include: • Mean Corpuscular Volume (MCV).• Mean Corpuscular Haemoglobin (MCH).• Mean Corpuscular Haemoglobin
Concentration (MCHC).
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MCV
• Mean cell volume• MCV is average size of RBC• MCV = Hct x 10
RBC (millions) • If 80-100 fL, normal range, RBCs considered
normocytic• If < 80 fL are microcytic• If > 100 fL are macrocytic • Not reliable when have marked anisocytosis
.
Value:
• MCV provides good assessment of RBC size, It detects :
• microcytosis, found in iron deficiency & thalassaemia.
• macrocytosis, found in B12 & folate deficiency
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MCH
• MCH indicates the mean of Hb content in RBC.
• MCH is average weight of hemoglobin per RBC.
• MCH = Hgb x 10 RBC (millions)
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MCHC• MCHC is average hemoglobin concentration
per RBC • MCHC = Hgb x 100
Hct (%) • If MCHC is normal, cell described as
normochromic • If MCHC is less than normal, cell described as
hypochromic • There are no hyperchromic RBCs
Value:
• MCHC is reflect the concentration of Hb in RBC.
• MCHC is used to differentiate normochromic from hypochromic anaemia
Always correlate RBC morphology with RBC indices .
• Re - check results in discrepancy .• MCHC is better determined than MCH,• This is because PCV measurement is more
accurate than RBC count.
Sources of Error in RBC Indices :
• All errors of RBC, PCV & Hb, cause wrong results in RBC indices.
REFERENCE RANGE FOR ERYTHROCYTE INDICES
MCV 80 – 100 fL
MCH 27 – 32pg
MCHC 32 – 36 %
Value Formula Normal Range
MCV (ƒl)
MCH (pg)
MCHC (x 100%w/v)
PCV (%) x 10RBC (millions / mm3 )
Hb (g/100ml) x 10RBC (millions / mm3 )
Hb (g/100ml) x 100PCV (%)
(80-100)76 – 96 ƒl
27 – 32 pg
32 – 36%