What a lab report contains
Most lab reports follow the same pattern. At the top are the details of the person and the sample: name, age, sex, the date the sample was collected and the date it was reported, the name of the lab and often the doctor who asked for the test. Check these first. A report with the wrong name or date is worth raising with the lab.
Below that is a table with one row for each test. A row usually has the name of the test, your result, the unit, the reference range and sometimes a flag. Tests are often grouped into panels, such as a lipid profile or a complete blood count, so one report can hold dozens of rows.
At the end there may be comments from the lab: how the sample was handled, what method was used or a note about a result. These are easy to skip and are sometimes the most useful part.
The result and its unit
The result is the number the lab measured. It means nothing without its unit, which is printed next to it. The same test can be reported in different units by different labs, for example milligrams per deciliter in one and millimoles per liter in another. A cholesterol value in one unit cannot be compared with a value in the other without converting it.
When you compare two reports, look at the unit before the number. If the unit differs, the numbers are not directly comparable.
The reference range
The reference range is printed beside each result. It is the range the lab uses to describe results it considers typical for the people it tested with that method. It is the lab's own range for its own method, which is why it is printed on every report.
A result inside the range is described as within range, and a result outside it is flagged. Neither tells you the whole story. A value outside the range is a prompt to ask your doctor, not a conclusion. A value inside the range does not mean that nothing needs attention. Your doctor looks at the result together with your age, your history, your medicines and how you feel.
Flags: H, L and other marks
Labs mark results that fall outside the range. An H usually means high, above the range, and an L means low, below it. Some labs use an asterisk, bold type or the words High and Low. A few use stronger marks, such as the word Critical, for results that need quick attention from a doctor.
Flags are not standard across labs. Read the key at the bottom of the report if there is one, and do not assume that a mark means the same thing as on a report from another lab.
Why two labs can give different answers
Labs use different instruments, methods and ranges, so the same blood sample can produce slightly different numbers and different ranges at two labs. That is normal. For this reason, compare results from the same lab when you can, and always read each result against the range printed on its own report.
Questions to ask your doctor
Write your questions down before the visit. These are a good start:
- What does this result mean for me, given my age, my history and my medicines?
- Is this value expected, or should it be checked again?
- When should I repeat this test, and should I do anything different before the next one?
- Does any of my medicines or supplements affect this result?
- Which results should I keep an eye on from report to report?
Keep your reports together
One report is a snapshot. A set of reports over the years shows direction. Keep every lab report, with its date, in one place, so that you and your doctor can look back.
MyCareTrack's lab report scanner reads a photo of a report test by test, shows each result next to the range printed on your own report, marks the results above or below it and saves the report on your timeline.