The tricarboxylic (TCA) or Krebs cycle is the "central hub of cellular metabolism" that takes place within the mitochondria. It is a series of sequential chemical reactions that generate cellular energy in the form of ATP. In addition, the cycle provides intermediate metabolites that are utilized in the biosynthesis of amino acids and fatty acids as well as reducing agents such as nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2) that are used in numerous biochemical reactions. The dysfunction of the TCA cycle is recognized for its association in neurodegenerative and cardiovascular diseases, metabolic syndromes, tumorigenesis and aging. Hence, being able to measure the activity or flux of the TCA cycle either in vitro or in vivo holds significant clinical significance. Almost all studies are based on in vitro approaches except NMRS based studies that involve multiple non-validated assumptions.