Blood test abbreviations: what Hb, MCV, CRP and ALT mean

Each line usually follows the same pattern: the name or abbreviation of the test, your result, the unit and the reference range. Some labs add a column for flags and your previous result.

• Panels: results are often grouped. In the UK you'll see FBC (full blood count), U&E (urea and electrolytes) and LFTs (liver function tests); in the US, CBC (complete blood count), BMP or CMP (basic or comprehensive metabolic panel) and a lipid panel.
• Units: the same value can come in different units. The UK reports glucose in mmol/L and HbA1c in mmol/mol, the US in mg/dL and percent. Only compare results with the same unit.
• Reference range: the range in which most healthy people's results fall, usually the middle 95 percent of a healthy reference group (Liver UK on reference ranges). It depends on the lab, the method, your age and often your sex.
• Flags: H marks a result above the range and L one below it; some labs use arrows, an asterisk or color instead. HH or LL can mark a critical result. Check the legend on your report.

The blood count measures the cells in your blood and describes the red blood cells in more detail. The differential splits the white blood cells into their types.

These results often appear on the same report as the blood count. Liver and kidney values are also checked as part of a general check-up, before a treatment or with regular medication.

Some of these values depend strongly on when the blood was taken. Glucose and triglycerides change after eating, which is why you may be asked to fast.

Because the reference range covers only the middle 95 percent of healthy people, about one in twenty healthy people falls outside it on any single test. The more tests are run, the more likely one flag turns up without anything being wrong.

• Patterns: results mean more together, for example low hemoglobin with low ferritin and a small MCV.
• Trends: a clear change since your last test often says more than one measurement.
• Circumstances: food, exercise, infections, medication or pregnancy can shift results.

Interpreting them is up to your doctor, who knows your symptoms, history and earlier results. If something is unclear, ask the practice instead of waiting for your next appointment. With acute symptoms, contact urgent care or, in an emergency, call the emergency number.

Scan your report with ExplainThisDoc or import the PDF from your patient portal. The Pro explanation goes through it value by value: what each test measures, whether it is flagged and what the lab's comment says. The free Light analysis gives you a first overview; it runs with Apple Intelligence on supported devices and in supported languages. The explanation helps you understand, but it is not a diagnosis and doesn't replace talking to your doctor.

Search your archive for “lab” to find earlier reports for comparison, and note your questions right on the report so you have them ready at your appointment. More on reading the whole report is in the guide Understand blood test results.