β-Hydroxybutyrate (β-HB; 3-hydroxybutyric acid) is produced in the liver, mainly from the oxidation of fatty acids, and exported to peripheral tissues for use as an energy source. Measurement of β-HB can provide a reliable index of the level of normal ketosis as well as detect…

Pyruvate (pyruvic acid) is a key intermediate in cellular metabolic pathways and is derived primarily from glucose via glycolysis. Abnormal blood pyruvate levels are reported in a number of disorders including shock, liver disease, congestive heart failure, diabetes mellitus, thiamine deficiency,…

D(−)-Lactate is a stereoisomer of lactate and is present in blood at only 1-5% the concentration of L(+)-lactate. Exogenous sources of D-lactate include fermented foods such as yogurt, sauerkraut, and pickles. D-lactate is normally produced in the gastrointestinal tract, mainly by…

Glucose-6-phosphate (G6P) plays a key role in the homeostatic regulation of blood glucose levels by participating in glycolysis, glycogen synthesis, gluconeogenesis, and can be metabolized to NADPH, enabling protection against oxidative damage. Disruption of G6P activity leads to glycogen storage…

L(+)-Lactate is the major stereoisomer of lactate formed in human intermediary metabolism. The lactate to pyruvate ratio reflects the redox state of the cell and describes the balance between NAD+ and NADH, which is dependent on the interconversion of lactate and pyruvate via lactate dehydrogenase…