Why would there be different published values for the normal range of a particular measurement? why do these values have to be updated periodically?

Answer and Step-by-step explanation:

For general measurements, different people or organizations normally make slightly different measurements. Measurements are never a hundred percent accurate.

The published values are usually updated because in the modern world of discoveries, change is the only constant thing. As new discoveries roll in or not, it becomes necessary to update the current standards; no change in the updated value means the old standards hold, and any change is also updated in the published update.

For health standards/ranges, Different countries have different standards of health

And this requires regular updating because standards of health changes frim time to time.