Why to references vary between labs?

[mtk0925]

According to some labs my blood work is normal range. I go to quest and their reference range for ALT and AST is under 29

Other labs are under 40

Then another is under 55 and 48 so idk I wonder if mine would be different elsewhere

[Fibro2021]

Each laboratory uses different types of equipment and different research methods. Therefore laboratory sets its own ranges of reference values depending on the equipment used and the method of analysis. The laboratory must indicate on the results form the reference interval approved by that laboratory.

[Roy1955]

It's the same as measuring temperature in Fahrenheit or centigrade, same as measuring distance/length in inches or meters.The numbers are different but the end results the same.

[mtk0925 in reply to Roy1955]

I asked my cousin who is a dr she’s a cardiologist but she informed me they also use different population samples to determine a normal range. She said obviously go by the lab I used