Types of blood tests: the main panels and what each measures

A panel is a group, not a list

What arrives as thirty numbered lines is really a handful of small panels, and inside each one the lines are meant to be read against each other. Hemoglobin with MCV and ferritin. ALT with AST and GGT. Creatinine with eGFR and your hydration.

That is why reading a report top to bottom rarely works, and why each page here explains a panel rather than a marker.

Why a single value says little

A single out-of-range number, read on its own, is the quickest way to the wrong conclusion. The same raised ALT does not mean the same thing after a bout of flu, after a heavy dinner, or after starting a new medicine.

So every page in this section starts from the group: which lines make it up, which one is read first, and which combinations are worth a question to your doctor.

What a routine panel shows, and what it does not

Routine blood work describes how a few large systems are behaving today: blood cells, sugar, kidneys, liver, thyroid, lipids, iron. It is not a cancer screen, it does not test for most infections, and it leaves out vitamin D or B12 unless they were asked for.

More lines do not buy more protection. A Cochrane systematic review of 17 randomized trials and 251,891 participants found that general health checks offered to adults had no effect on total, cancer or cardiovascular mortality. In one of those trials, people offered checks received 20% more new diagnoses over six years, without any change in outcomes.

Some lines are fragile for technical reasons rather than medical ones. Potassium is the classic case: red cells damaged during collection release it into the sample and raise the result, which is why laboratories measure the degree of hemolysis and reject samples beyond a threshold.

Four readings that changed recently

Four lines are read differently today than a few years ago, which matters whenever you compare a new report with an older one.

Where to start

If your report is a long sheet, begin with the full blood panel guide, which explains how the groups fit together and what a check-up can and cannot tell you. Then go to the group that carries your flagged lines: blood count, metabolic panel, lipids, liver, kidneys, thyroid or iron.