Do I need to understand the method names?

No. They are background detail. Focus on the result, its unit, the range and any flag.

Why does one test flag and another not?

Each value is read against its own range, so only the tests outside their range are flagged.

Are HH and LL more serious than H and L?

They mark a larger step outside the range. How much it matters still depends on the test and your overall picture.

Should I use the same method each time?

For tracking a value over time, the same lab and method makes comparison cleaner, though it is not essential [CLSI, 2010].

This is an independent guide to report layouts. It is not affiliated with, endorsed by, or partnered with any laboratory. It describes layout conventions only.

How to read a report with method and flag columns

Some reports add two extra columns: a method column and a flag column. The method names the technique the lab used, such as an enzymatic method. The flag marks any value outside the range with an H for high or an L for low [CLSI, 2010].

Last reviewed: 2026-08-16

What does the method column tell me?

It names the technique used to measure each test. Different methods can give slightly different numbers for the same sample [CLSI, 2010].

You do not need the detail; it is there so your doctor can compare results correctly.

How is the flag column used?

It shows H when a value is above the range and L when it is below. Some reports use HH or LL for a very high or very low value.

A flag means worth a closer look, not that something is wrong.

Does the method change my range?

It can. Because methods differ, each lab sets its range to match its own method [CLSI, 2010].

This is why you compare your result with the range printed on the same report.

Frequently asked questions

Do I need to understand the method names?: No. They are background detail. Focus on the result, its unit, the range and any flag.
Why does one test flag and another not?: Each value is read against its own range, so only the tests outside their range are flagged.
Are HH and LL more serious than H and L?: They mark a larger step outside the range. How much it matters still depends on the test and your overall picture.
Should I use the same method each time?: For tracking a value over time, the same lab and method makes comparison cleaner, though it is not essential [CLSI, 2010].

Sources

CLSI (2010) — Clinical and Laboratory Standards Institute (reference intervals and report presentation)

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