Red Blood Cell (RBC) Indices Calculator

RBC indices explained

The above calculator estimates the three RBC indices based on haemoglobin and haematocrit values and on red blood cell count.

RBC indices reflect characteristics of the circulating red blood cell population: size, shape or Hb composition.

These can be measured directly in laboratory based on a small venous blood sample, obtained following a normal blood test.

They help differentiate between types of anemia, a condition in which the number of red blood cells or the quantity of haemoglobin fall below normal.

There are three variables that are used to calculate the RBC indices:

■ Hemoglobin: The protein responsible with oxygen transport in the blood with normal values between 12 and 18 g/dL, with slight variation for gender.

■ Hematocrit: The ratio of RBC to total blood volume, with normal values between 37 and 52% and determined via centrifugation of blood.

■ Red blood cell count: The number of RBC in the sample, with normal range between 4.2 and 6.3 x10¹²/L.

The table below summarises the formulas (in which the variables discussed above are employed) and normal values for each RBC index:

Mean Corpuscular Volume

MCV offers information about the average size of red blood cells and is measured in femtoliters, which is equivalent to 10^-15 L.

Reference values are between 80 and 96 fL, according to the American Association for Clinical Chemistry. Other sources provide normal values between 80 and 100 fL or 83 and 97 fL and there may be some laboratory variation too.

MCV in fL = (Hematocrit %) / (RBC x 10¹²/L) x 10

Erythrocytes with normal MCV are called normocytic, those with high MCV are called macrocytic and those with low MCV are microcytic. The following table describes the types of anemia reflected by the erythrocyte size:

This is deemed the most important of the RBC indices because it also contributes to the calculation of and the red blood cell distribution width.

Mean Corpuscular Hemoglobin

MCH indicates the average weight of hemoglobin in the RBC blood sample. The measurement unit is picogram, which is equivalent to 10^-12 grams.

The normal range for adults is between 27 and 33 pg according to the American Association for Clinical Chemistry but other sources also provide 27 - 31 pg.

The formula is:

MCH in pg = (Hemoglobin in g/dL) / (RBC x 10¹²/L) x 10

Macrocytic erythrocytes tend to have a larger concentration of haemoglobin. MCH levels in the PLT/MCH ratio can help in the differentiation of microcytic anemia causes: iron deficiency anemia (IDA) vs combined deficiency B12 and iron, IDA-B12 anemia.

Mean Corpuscular Hemoglobin Concentration

MCHC determines the average concentration of hemoglobin in the red blood cell sample in g/dL. According to the American Association for Clinical Chemistry, normal adult values are between 33.4 and 35.5 g/dL. Other sources indicate a wider range: 32 - 36 g/dL.

MCHC in g/dL = (Hemoglobin in g/dL) / (Hematocrit %) x 100

Lower than normal MCHC values indicate hypochromic RBCs, normal values are characteristic for normochromic erythrocytes whilst greater than normal MCHC values indicate hyperchromic cells.

References

1. The McGill Physiology Virtual Lab (2016) Blood cell indices > MCV and MCHC.

2. Sharma R. (1990) Chapter 152, Red Cell Indices. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition.

3. Bessman JD, Gilmer PR Jr, Gardner FH. Improved classification of anemias by MCV and RDW. Am J Clin Pathol. 1983; 80(3):322-6.