Luay A. Al-Helaly

The ratio of Hct to Hb in healthy people is usually three to one. Based on this assumption, you can also convert the hematocrit value to hemoglobin by dividing it by 3.

Gregory Barshtein

thanks for your reply..

Do you think these accounts are correct?

And what is the source of these calculations

Dear you can convert Hct to haemoglobin using 3 rule.

Luay A. Al-Helaly

This relation is true if MCHC is close to 33 g/dl.

We can calculate that but there should be two things:

1- The RBC indices should be normal.

2- We should put in our mind that, this calculation by dividing by 3, it is roughly estimated and that not pricisely calculated.

Remember the basic formulas of blood cell counting:

HCT = RBC * MCV

HGB = RBC * MCHC

Median of MCHC is about 330 g/l. If erythrocytes have a normal size distribution (median about 90 fl), and they contain the normal amount of hemoglobin (around 30 pg/cell), then you can use a constant factor. A lot of assumptions.

All these are arbitrary and when hemoglobin can be done with much easier way and faster, I DO NOT see any logic in doing so.

If erythrocytes have a normal size distribution (median about 90 fl), and they contain the normal amount of hemoglobin (around 30 pg/cell), then you can use a constant factor.If it is abnormal, it can not be done, and there is no exact source for this

Yes, though no exact source or reference.

Olabanji Aleruwa

thanks for your reply..

When I read the question again, I realized that it is the question of calculating some parameter by two ways. Sorry if I am wrong, but in the hematology analysers, it is MCV, which some counters derive by PCV divided by RBC, or directly. Here the estimation of PCV is done by adding the pulses of electrical impedence produced in a given volume of diluted blood; or as each red cell passes through the aperture, the MCV is determined by converting the electrical impedence (mV) in volume (fl). As more and more red cells pass through in the single cell profile, average fl is constantly calculated (MCV) and multiplying by RBC, it calculates PCV. Hemoglobin is always measured by the lysed diluted blood which passes through a small detector colorimetrically. It is very easy and accurate by colorimetric estimation, than by speculating that MCHC is ALWAYS (?) 33.3 g/dl (or 333 g/l), which is never there.

Thank you very much for your answer and good explanation for this question.

Ramesh Z. Patel

You have to consider the difference between "calculating" and "estimating":

Haemoglobin value cannot be calculated in any way but only measured directly by colourimetric methods. The " three times" rules such as RBC x 3= HGB; HTC/3= HGB) (Cembrowski, George S., and Gwen Clarke. "Quality control of automated cell counters." Clinics in laboratory medicine 35.1 (2015): 59-71) are a coarse estimate which can be used when only an approximate result is sufficient. Of course, derived parameters in whose calculation formula there the HGB is present (MCHC, MCH) cannot be used for the simple reason that, lacking HGB value, they cannot exist.

Thanks for your contribution

Antonio La Gioia