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 L/L Females L/L MaleFemaleAverage PCV %

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.

9 Calculation Of Red Cell Indices

10 RBC Indices RBC indices include: Mean Corpuscular Volume (MCV). Mean Corpuscular Haemoglobin (MCH). Mean Corpuscular Haemoglobin Concentration (MCHC).

11 MCV Mean cell volume MCV is average size of RBC MCV = Hct x 10 RBC (millions) If 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

13 MCH MCH indicates the mean of Hb content in RBC. MCH is average weight of hemoglobin per RBC. MCH = Hgb x 10 RBC (millions)

14 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 %

ValueFormulaNormal Range MCV (ƒl) MCH (pg) MCHC (x 100%w/v) PCV (%) x 10 RBC (millions / mm 3 ) Hb (g/100ml) x 10 RBC (millions / mm 3 ) Hb (g/100ml) x 100 PCV (%) (80-100)76 – 96 ƒl 27 – 32 pg 32 – 36%