谷丙转氨酶（英文：Alanine transaminase，缩写ALT）是一种转氨酶（EC2.6.1.2，存在于血浆及多种身体组织中，但最常见与肝脏关联。也叫血清谷氨酸丙酮酸转氨酶（serum glutamate pyruvate transaminase，简称SGPT）或丙氨酸转氨酶（alanine aminotransferase，简称ALAT）。

Alanine transaminase (ALT) is a transaminase enzyme (EC2.6.1.2). It is also called alanine aminotransferase (ALAT) and was formerly called serum glutamate-pyruvate transaminase (SGPT) or serum glutamic-pyruvic transaminase (SGPT) and was first characterized in the mid-1950s by Arthur Karmen and colleagues. ALT is found in plasma and in various body tissues, but is most common in the liver. It catalyzes the two parts of the alanine cycle. Serum ALT level, serum AST (aspartate transaminase) level, and their ratio (AST/ALT ratio) are commonly measured clinically as biomarkers for liver health. The tests are part of blood panels.