Alanine aminotransferase (ALT)
ALTAlanine aminotransferase is an enzyme concentrated in liver cells, measured in blood tests as a marker of possible liver injury.
ALT normally stays inside liver cells and appears in the bloodstream only in small amounts. When liver cells are stressed or damaged, the enzyme leaks out and blood levels rise, which is why ALT is included in routine liver panels. Laboratories report the result in units per liter alongside a reference range, and clinicians look at the size of the rise and whether other markers, such as AST and bilirubin, move with it.
ALT matters in cannabinoid discussions because clinical trials of prescription cannabidiol recorded ALT elevations in some participants, more often at higher doses and when taken with valproate. Regulators therefore recommend liver enzyme monitoring for people on prescription CBD. In the veterinary setting, ALT is also part of the standard blood chemistry panel, and some canine studies have reported changes during CBD administration. An elevated ALT is a signal for further evaluation, not a diagnosis by itself.