Hi All
Hope you are all doing well with lockdown etc., 🌈
Can anyone tell me - Why are Lab ranges important? What do they tell me with regards to my blood test results?
.
Are they THEIR ‘normal ranges’?
.
Why do I need % with regards to my result in relation to their range?
.
Preparing for an Endo appointment and just trying to get my head round it all.
Thanks in advance 😀 x
Why are Lab ranges important?
Suppose you have a test for ferritin (iron stores) and the result is 25.
The reference range could be something like 10 - 200. Your result is within the reference range so your doctor will tell you it is "normal".
The range could be 30 - 300. Your result is below the reference range and your doctor might decide to treat you for low iron. Miracles occasionally happen.
Suppose the reference range is 13 - 150 (a common range for ferritin in the UK), and you asked the forum for an interpretation... We would most likely tell you that the optimal level for ferritin is mid-range i.e. around 80 - 85 in this case and your level of 25 is way too low for good health and is likely to make you suffer from lots of low iron symptoms.
In each case the decision about what to do is determined by the range. Different labs have different methods of testing and may have different reference ranges. You need the range to decide what the result actually means.
So the Dr can say to me - you are within the range therefore no need to treat? Why do some lab ranges differ? How or who sets those ranges?
Labs all have their own testing protocols and methods of testing. Different manufacturers' testing machines might give completely different results because the method of testing is different.
To determine their ranges the "proper" way for labs to do it is to test a sample of "healthy" people, put the results in order of size from smallest to largest, and then take the results from the middle 95% and call that the range.
There are lots of problems with this. First of all, I've never heard of a lab which interviews people about their health to determine who is healthy and who is not before using them to determine the range. The chances are quite high that their group of subjects have some health problems of their own. I have read that labs often use their own staff as their test group - but I don't know if that is true. The number of people tested is often tiny too.
Secondly, by using the middle 95% of the results they are assuming that the bottom 2.5% and the top 2.5% might have some kind of undiscovered health issue. But in the case of ferritin, which I used earlier, the number of people who suffer from low iron or iron deficiency is huge. Pick a group of supposedly healthy people and quite a few will be low in iron. But their results will form part of the range anyway.
The other thing is that in the case of minerals and vitamins what constitutes a healthy level? Using the example of vitamin D the healthy level for this was set decades ago as the level required to avoid rickets. There has never been any attempt to find out what levels of vitamin D gives people optimal health. They just have to be sure that the people they test don't have rickets.
Lab ranges show the range of results considered normal for that particular area of the country and for processing method used by that lab.
Within the set of ranges for your lab you need to find which level suits you best. I call this your optimal normal. For example my lab uses 10 - 25 as the range for FT4. Now doctors would accept the result as normal at 10 and they would accept it as normal at 25. The individual though might not feel well at either of those and only by adjusting medication can we find where in the normal range we feel best - optimal normal.
% through range can be useful when you have had blood test at two different labs where the ranges are different. Your FT4 at one could be 16 and at the other 14 but by comparing how far through its range the 16 is and how far through its range the 14 is you can judge how similar the result is.
% through range helps you to compare FT4 and FT3 results. For many the body likes these to be balanced. My FT4 was 19 (10 - 25) and my FT3 was 4.5(4.0 - 7.0). To compare these results I worked out that FT4 was 60% through its range and FT3 16.7% through its range. There was a mismatch and my FT3 needed to be higher. I used this to show that I had a conversion problem and that levo alone was not working for me.
Why do I need % with regards to my result in relation to their range?
Imagine you get the following result for ferritin from two consecutive tests a few months apart :
Test 1 : 67.7
Test 2 : 51
It appears that ferritin level has dropped quite substantially.
But if I add in the percentage through the range :
Test 1 : 67.7 14%
Test 2 : 51 28%
You can see that the second percentage is larger than the first result and ferritin level had actually improved.
The difference between the two is that the reference ranges were different.
Test 1 : 67.7 14% Range : (13 - 400)
Test 2 : 51 28% Range : (13 - 150)
If you want to compare two results that have two different reference ranges the easiest way to do it is to compare the percentage through the range.
Previous post ....lots of low vitamin levels
healthunlocked.com/thyroidu...
Recommend getting FULL thyroid and vitamin testing
Also are you sticking to strictly gluten free diet
Oh don’t worry Slow Dragon ... I am going to next appointment fully equipped! 👋
Yes taking all supplements. Getting a Medichecks on Thursday with the discount they offer on Thursdays. Gluten ... yes with occasional slip up by accident but getting there. 😀
The only things I know about high ferritin are :
1) It could indicate the patient has hemochromatosis.
2) It could indicate inflammation problems.
3) Doctors don't usually care about ferritin until it is roughly 800+.
"Normal range" is not a good term. Generally, "reference interval" or "reference range" are preferred terms.
This freely accessible paper explains at great length why:
The normal range: it is not normal and it is not a range
Martin Brunel Whyte 1,2,
Philip Kelly 1
Abstract
The NHS ‘Choose Wisely’ campaign places greater emphasis on the clinician-patient dialogue. Patients are often in receipt of their laboratory data and want to know whether they are normal. But what is meant by normal? Comparator data, to a measured value, are colloquially known as the ‘normal range’. It is often assumed that a result outside this limit signals disease and a result within health. However, this range is correctly termed the ‘reference interval’. The clinical risk from a measured value is continuous, not binary. The reference interval provides a point of reference against which to interpret an individual’s results—rather than defining normality itself. This article discusses the theory of normality—and describes that it is relative and situational. The concept of normality being not an absolute state influenced the development of the reference interval. We conclude with suggestions to optimise the use and interpretation of the reference interval, thereby facilitating greater patient understanding.
So every member of every family with haemochromatosis genes is aware of their status? Surely there has to be a first discovery in every family it affects? Nobody ever dies of haemochromatosis that was undiagnosed in life?
The refusal to test is further evidence of a health system being destroyed by the constant demands to save every penny.
You might like this link :
Why is there a range for TSH ETC. 
Variations in lab ranges for TSH receptor antibodies
Confused about FT3 result because of different lab range - over range?
Why thyroid range keep changing?
Why do ranges matter?
