Hemoglobin And Hematocrits Are The Same - CRIT CLOUD

Hemoglobin is NOT Different from Hematocrit... Once and for All!

26/8/2015

• In fact, virtually all haemoglobin in our blood is contained within erythrocytes
• Therefore, whether the amount of Hb per litre of blood is determined or the blood’s volume occupied by the Hb filled erythrocytes is determined, similar information is gained.

• Nijboer at al. have brilliantly proven that Hb and Hct correlate in all ranges and all patients and also nicely show this in their figure 1 (see below)
• The only rare exceptions are macrocytic and polycytemic anaemia in which the Hct is defined by erythrocytescontaining a normal mean corpuscular Hb concentration

• Hemoglobin is NOT different from Hematocrit
• Both parameters provided identical clinical information

"The only rare exceptions are microcytic and polycystic anaemia" -- I don't know about polycystic anaemia, but microcytic anaemia isn't rare!

Thank you I work in a lab we occasionally have to cancel and re-order blood work, I had a order for Hemoglobin and Hematocrit I decided to order only the hemoglobin and I begin to doubt myself as if I did the correct thing by ordering just the hemoglobin instead of ordering the two of them together as the doctor sent down to the lab.

Hi Jonathan, thanks indeed for your feedback! This shows what a simple exchange of one letter can do! It's mAcrocytic anaemia of course... Corrected now! But hey, thanks for making this post peer reviewed, Tim ;)

thank you for this... I am an MD trying to explain this to a community group and this made it clear

Thank you for your post. Clinically, there is no need to measure both in most cases. However, can you confirm that for research purposes (estimating prevalence of anemia) if one clinic is collecting hematocrit and the other hgb, these clinics can't be compared regarding the level of anemia? I'm seeing Quinto, et al 2006 'Relationship between haemoglobin and hematocrit in the definition of anaemia' in Tropical Medicine and International Health, vol II (8). 1295-1302. The posted comments also suggest this is the case, right?. (I'm an MPH student in public health, so I apologize if this is a very novice question to ask....I'm a novice!).

Dear Alicia, Thanks for your comments on this post. As mentioned in the short summary in most clinical scenarios there is no real difference between hemoglobin and hematocrit. As pointed out above, there are some exceptions like macrocytic and polycytic anemia in which the hematocrit is defined by erythrocytes not containing a normal mean corpuscular hemoglobin concentration. Another theoretical exception might be a state of relevant hemolysis in which free plasma hemoglobin would occur. The question is also what sort of information you are looking for. If you're looking into oxygen capacity and oxygen binding capacity you will be better off measuring hemoglobin. In polycytemic states hematocrit might be of greater interest. Finally, comparing two different kind of parameters for research purposes is never a good idea as unintended bias might occur. Hope this helps, best regards!

So if they are the same the ratio Hct/Hgb should be constant ~ however mine has changed from 3.5:1 to 3:1 in the last two years. Obviously not the same !

Thanks for the post.! can you throw some light on how it may vary in newborn especially in a preterm, where there is increased Hct/Hb and it would change as the baby grows.? Has it any bearing on the different cutoff we use to transfuse these growing preterm

Really nice...Had this doubt for long time... you explained it clearly..

A correlation on a scatter plot is not proof of equivalence. For example if the gradient is not 1 then there will be a systematic difference. There is a close correlation between heart rate and respiratory rate but does not mean they contain the same information. Bland-Altman plot would be more informative surely

Dear Timothy Please inform is this is also the case with blood gas analyser results. Do they use the same techniques to measure as you have stated. I am an anaesthetist and we regularly look at arterial blood gas sample results and these show the Hb AND the haemoatocrit. Does what you have stated apply here too?

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