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Red blood cell distribution width (RDW or RDW-CV or RCDW and RDW-SD) is a measure of the range of variation of red blood cell (RBC) volume, yielding clues about morphology. [ citation needed ] Erythropoietic precursor indices
Measure the RBC index in cells/μL. Take the reciprocal (1/RBC index) to convert it to μL/cell. / = / 2. The 1 μL is only made of a proportion of red cells (e.g. 40%) with the rest of the volume composed of plasma.
The widely used [21] rule calculating normal maximum ESR values in adults (98% confidence limit) is given by a formula devised in 1983 from a study of ≈1000 individuals over the age of 20: [22] The normal values of ESR in men is age (in years) divided by 2; for women, the normal value is age (in years) plus 10, divided by 2.
RDW-SD is calculated as the width (in fL) of the RBC size distribution histogram at the 20% height level. This parameter is, therefore, not influenced by the average RBC size (mean corpuscular volume, MCV). [7] RDW-CV (expressed in %) is calculated with the following formula: RDW-CV = (1 standard deviation of RBC volume ÷ MCV) × 100%. [8]
The Mentzer index, described in 1973 by William C. Mentzer, [1] is the MCV divided by the RBC count. It is said to be helpful in differentiating iron deficiency anemia from beta thalassemia trait. [2] [3] The index is calculated from the results of a complete blood count.
Women have about 4–5 million red blood cells per microliter (cubic millimeter) of blood and men about 5–6 million; people living at high altitudes with low oxygen tension will have more. Red blood cells are thus much more common than the other blood particles: there are about 4,000–11,000 white blood cells and about 150,000–400,000 ...
In this article, all values (except the ones listed below) denote blood plasma concentration, which is approximately 60–100% larger than the actual blood concentration if the amount inside red blood cells (RBCs) is negligible.
Still, many instances measure MCHC in percentage (%), as if it were a mass fraction (m Hb / m RBC). [ 2 ] [ 3 ] Numerically, however, the MCHC in g/dL and the mass fraction of hemoglobin in red blood cells in % are identical, assuming an RBC density of 1g/mL and negligible hemoglobin in plasma.