Blood Test Markers
Explainers on the markers that show up in routine bloodwork — what each number means, how to read reference ranges, and which trends matter more than a single result.
LiverBlood Test MarkersWhat does high AST mean?
A high AST means there's more of an enzyme called aspartate aminotransferase in your blood than usual — often because some of the cells that hold it have released it. Those cells live in your liver, but also in your muscles, your heart, and your red blood cells. It's a common and usually mild finding, and on its own it rarely tells the whole story. What it means depends on how high it is, what's sitting next to it on the panel, and where it's been heading over time.
7 min read
B12 DeficiencyVitamin B12What does low B12 mean?
Low B12 means your body doesn't have enough vitamin B12 — also called **cobalamin** — circulating to keep up with what your cells need it for. That's a long list: making red blood cells, copying DNA, and maintaining the myelin sheath that wraps your nerves so signals travel cleanly. When B12 runs low, those processes get sloppy. You feel it before the bloodwork shows it.
6 min read