Hill's Prescription Diet w d Multi Benefit Weight GI & Glucose Mana My Animal Dispensary L carnitine is primarily synthesized in the liver from the amino acids lysine and methionine through a series of four enzymatic reactions, with the liver and kidneys converting the precursor butyrobetaine into active Role of carnitine in disease Nutrition & Metabolism Springer Nature Link 3 Ways to Give LCarnitine to Cats with Fatty Liver wikiHow Pet