Normal ALT

[Liverpatient]

Hi, my local laboratory operates with normal ALT levels as follows: for men, <70U/L, and women,<45U/L. However on the guidlines of WHO and many other scientific works I hvae read the normal for men to be <30U/L, and women<19U/L.
The question: is my lab operating on a wrong range, because their normal ranges are more than double of those recommended by WHO? For example my last ALT level was 37U/L, which is well below the upper limit of normal according to my local lab; but according to the WHO, it is a bit higher than the upper level. So I'm confused what to believe.
PS: on the WHO recommendations I have also read that local lab ranges should be applied as regards ALT.

[Aduiski]

The hepatitis B guidelines are slowly converging on what is the upper normal limit for ALT...most of them take 30 as UNL for males and 19 for females.

[stef2011]

there is also a study based on disease free liver in the future and the values were very low to get very high percentages of disease free liver, i dont remember exact values but they were about less than 20.also the percentages of disease were low for alt 20-25.
but again the meaning of this study is very limited if you check liver by fibroscan every year you ll be disease free anyway because as you see increase of kpa values you have all the time to correct diet/food quality and so on even with alt around 30 or more

the study was posted here so using research tool it should be possible to find the post

[StephenCastlecrag]

The ALT ULN is based on statistics, that is, from samples of ALT values taken from a reference population. From Wikipedia:
"The standard definition of a reference range for a particular measurement is defined as the prediction interval between which 95% of values of a reference group fall into, in such a way that 2.5% of the time a sample value will be less than the lower limit of this interval, and 2.5% of the time it will be larger than the upper limit of this interval, whatever the distribution of these values.[1]"
So the reference range from a Lab depends critically on the reference population sample it used to calculate the ULN. Some hospitals used ALT values from their patient samples, some Labs may use ALT values from their customers. Others may use a common national standard. So ULN can vary depend on the reference populations used. In order to say ALT is under the upper "NORMAL" limit, we would like the reference population to be from a healthy, liver disease-free population, and not just a random sample from those visiting a hospital, a Lab, or from an HBV/HCV endemic populations.
The problem is of course how do you ensure that your reference population is healthy?

[Aduiski]

The problem with labs that operate on very unusual ranges like ALT ULN being 70, is that you can not be sure whether their ranges are a) truly adjusted to the normal values, or b) it is the case that they are going by old range standards, or c) the mix of both a) and b).

Most modern countries have ALT ULN nowadays reduced to 30-40

[Liverpatient]

Hi Aduiski, I have checked on the labs in the country that I live in. Unfortunately, they all seem to operate on the same range, as I stated above. But I have read that these differences in reference values are natural, and one has to follow to the guidelines of local labs; the differences is arising from, among, other things, instruments and techniques of measurements used.

[Aduiski]

Find a different ,reliable lab which measures with lower threshold limits and test there on future

[Nasim65]

However, some labs have different ranges for “healthy” ALT levels, so you need to see what you lab identifies as normal. Some indicate that up to 50 is still healthy.