Acylcarnitine C4 Unit Converter

Acylcarnitine C4 refers to two four-carbon acylcarnitine species: butyrylcarnitine and isobutyrylcarnitine. Standard laboratory assays measure both forms together because they share the same molecular weight and cannot be separated by routine tandem mass spectrometry.

Butyrylcarnitine is produced during mitochondrial beta-oxidation of short-chain fatty acids, while isobutyrylcarnitine arises from the breakdown of the amino acid valine. Together, they reflect how well the body handles short-chain fat metabolism and branched-chain amino acid catabolism.

C4 is typically measured as part of a full acylcarnitine panel alongside markers such as C2 (acetylcarnitine), C3 (propionylcarnitine), and C5 (isovalerylcarnitine).

C4 acylcarnitine is produced inside mitochondria, primarily in the liver and skeletal muscle. Butyrylcarnitine forms during short-chain fatty acid oxidation, while isobutyrylcarnitine is generated from valine catabolism in tissues throughout the body.