CLL Support Association
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Blood Counts - how measurement units differ internationally

This one comes up regularly and perhaps it would be useful to repeat this again.

Newly diagnosed with CLL and then a quick check on Google brings up information on blood counts from both European sources and America (Canadian?) sources or Australian sources.

But the numbers are confusing and what is 10*9/L or 10*12/L..???

And what is an Absolute Count, my UK blood result just shows Total White Cell count and Lymphocyte Count.

Perhaps someone in the know can point to a website showing the differences, and how to convert the USA or Australian numbers, to what they might read on their UK blood results.

This would be a service to many readers.


8 Replies


Yes it is confusing - very! As you've observed, not only do the units vary, so does the nomenclature, what gets reported (and the format). Strangely, while the USA and Burma are the only countries still not metric, the US does use metric units for blood counts - just usually in different units from the UK and Australia. I'm not even sure this is consistent within the same country!

In addition to the sometimes considerable range differences for male and female, there are differences by country (different genetic mixes), age and testing laboratory. I've seen some reference ranges change over time on my results too - on one occasion it was when the measuring procedure/equipment changed.

I'd say that it is more important to know what's normal for you and look for any trends, which is why I track my results in a spreadsheet.

It may interest people to know how the ranges are calculated. Basically, the reference range quoted on your test results covers 95% of the healthy population where you live, so if one of your test result falls outside that range, then you could be one of the 1 in 20 healthy people that have results that are normal for them, but are outside of the normal distribution - or you could be ill. Again, this is why you need to know your baseline.

Here are the reference ranges for the UK

The same measurement units are used and the ranges are similar in Australia.

Here's a thorough but overwhelming reference, but without the quick correspondence table we want:

I find Wikipedia a very useful reference for understanding the function of the different blood components too.


"When you examine test results from different populations, you quickly discover that what is "normal" for one group of people is not necessarily normal for another population group."

"Whether or not your test result is within the laboratory reference range, consider it within the context of your personal circumstances and with the benefit of your own and your doctor's knowledge of your past medical and personal history, together with the results of any other investigations performed."

It would be good if someone can point us to a link showing the measurement unit differences between the Australia, Canada, the US, and the UK or perhaps we'll just need to put together our own comparison table.



Neil wrote :-

' It would be good if someone can point us to a link showing the measurement unit differences between the Australia, Canada, the US, and the UK or perhaps we'll just need to put together our own comparison table.'.

The above was what I was thinking of; so that if someone looks first at a USA / Canadian website they can then look at the figures and easily convert to say a UK figure or compare with the pages just received from their doctors.

A bit like when you go on Google and ask for a kg to Lbs conversion table.



It is very confusing.

The absolute lymphocyte count (ALC) on your UK panel results is pre calculated and given as a lymphoctye figure or LYMPH etc. I believe In the UK we get ours as a figure representing Cells X 10 to the 9 power per litre . whereas over the pond they use the microlitre, thus US counts seem thousands of times larger?

It is not the figure at one point in time that is important but trends over time. As Neil mentions " it is more important to know what's normal for you and look for any trends". Remember there is not just variability between how different countries calibrate. But there can be natural variability between your own results.(this is explained below)

This is a very informative article by Chaya Venkat at CLL Topics:

Complete Blood Count: lymphocytes

intro: "I want to let you in on a little secret: the medical jargon that patients find so intimidating is just that – jargon. Plumbers have their jargon, accountants and engineers have their versions, doctors’ jargon is no different. It is a short hand way that the members of the club talk to each other, because they all know what the jargon means, it saves time and it makes for efficient communication. It also has the added benefit of shutting out riff-raff like you and me, cloaking often very simple concepts in awe inspiring mystery. In reality, it is often nothing more than the ’secret handshake’ you must know before you are a full fledged member of these exclusive clubs. After reading these series of articles I promise you will be able to understand every single last number on your latest CBC report. This first article of the series will focus on lymphocytes, one variety of white blood cells."

CLL Topics:

Complete Blood Count: lymphocytes

Complete Blood Counts: Red Blood Cells

Blood Basics: Variability in CBC Numbers Trends Over Time Tell the Real Story

by Chaya Venkat

"Today I have had two friends who wrote to me with what they thought were significant changes in the absolute lymphocyte numbers, elated in one case and upset in the other.

I am a firm believer in developing a database with all your CBC numbers and graphing them if you can. Trends are much easier to spot in a graph, than they are in a jumble of numbers. The template provided under the Your Charts section may help you do just that.

But....please do not read a lot into every up and down in the CBC numbers. Recently, in an interview on HealthTalk, Dr. Keating said that about 95% of the lymphocytes reside in the bone marrow, spleen, lymph nodes etc. Only about 5% of the lymphocytes are in the peripheral blood.

Now, consider a situation where your lymph nodes swelled up a little in the last few days, just before your CBC blood draw. Let us say that instead of 95% of the lymphocytes, 96% of the lymphocytes are now sequestered in the lymph nodes, spleen, BM etc. That leaves only 4% in the blood, as opposed to 5% before. That is a 20% drop in the absolute lymphocyte count you would get in the CBC. But nothing has really changed, and there are the same number of CLL cells still in your body, overall.

Recently some members who happen to be jocks have reported that the absolute lymphocytes in the CBC go up if they have been exercising vigorously just before the CBC blood draw. Makes sense, the large muscle activity is what gets the lymphatic system pumping more vigorously (unlike the blood circulation, which is carried out by a pump, the heart, lymphatic system has no pump, and just depends on the action of various large muscles in the body to get the lymph fluid circulating). Exercise means there are no sluggish pools of lymph sitting around, some people find that the nodes seem to be more rubbery, less hard, after a vigorous work out (or even a hot bath!). Fewer lymphocytes get stuck in the lymphatic system means more are in the peripheral blood, even if the overall number has not changed one bit.

Another point to consider: say your absolute lymphocyte number last month was 15,000. and this month it went up to 16,500. A difference of 1,500. Now fast-forward to three years from now. Your absolute lymphocytes went from 80,000 to 88,000 in one month. Wow!! a change of 8,000 in just one month!! Hold on, look at it more closely. In the first example, change of 1,500 starting from a base of 15,000 is a 10% change, same as in the second case of 8,000 on a base of 80,000.

Actually, all the data I have seen from several people now suggests that the rate of growth of the CLL population is not a linear (straight line) relationship, it is more an exponential function. For the non-mathematicians, exponential function means the larger the number gets, the faster it will increase. That is why one of the criteria that is looked at is doubling time, not the actual number change. If the doubling time stays the same, your ALC number will climb from 10,000 to 20,000 in the same time that it takes to go from 30,000 to 60,000.

Trend lines and statistics are important, but you must take care to interpret them carefully."

Dr. Susan Leclair explains the meaning behind key tests about which CLL patients are curious. Understanding Your CLL Blood Tests: Immunoglobulin, Complete Blood Counts, Platelets and More

Earlier community discussion threads: absolute-lymohpcyte-count-alc-and-other-metrics cllsupport.healthunlocked.c...

Why we need to track the absolute lymphocyte count ((ALC) not white blood cell count (WBC) cllsupport.healthunlocked.c...


From the guidelines..

'The diagnosis of CLL requires the presence of at least 5 times 10^9 B lymphocytes/L

5 x 1,000,000,000 B lymphocytes per litre of blood...

Or 5000/µL micro litre... or 5K per micro litre...

in the peripheral blood.


Here are two direct comparison charts that compare common US units and SI units.



Very well found Mike - fairly comprehensive too.

I notice they don't agree on one of the confusing differences - platelets!!




I was so excited when I found your comparison charts and then so disappointed when I found that the red and white blood cell counts have no conversion. I wonder what that is all about?


SI is very common in blood counts, for things like lymphocytes etc. it may be expressed in mm3 or 10^9/L ... they are both metric, one is just a smaller quantity...

Wikipedia has an excellent reference on blood ranges...

Also go to Labtests Online and select your country, all the scales will be correct...


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