The present knowledge of intermediary metabolism is still incomplete; yet of the few well-established facts it is generally accepted that pyruvic acid is one of the most active intermediary compounds of living cells. Pyruvic acid participates prominently in the transformation of the three classes of foodstuffs: in the oxidation of carbohydrate as the terminus of the Embden-Meyerhof scheme of anaerobic glycolysis; in the introduction of protein to the tricarboxylic acid cycle through chemical interrelationships with alanine, and in the metabolic changes of fat through a 2carbon acetyl compound similar to acetic acid. Pyruvic acid is truly a "hub toward which converge carbohydrate, fat and protein in their catabolic and anabolic reactions" (Barron).
Since the early 1940's a sizable body of literature has appeared in regard to the role of pyruvic acid in the chemistry of biologic reactions. Thus blood pyruvate has been found elevated in decompensated cirrhosis, thiamine deficiency, malnutrition,
NORMAN SHRIFTER, MORTON D. KRITZER. Carbohydrate MetabolismII. Changes in the Serum Pyruvic Acid During Glucose-Tolerance Test in Normals, Diabetics, and Prediabetic Women. AMA Arch Intern Med. 1956;98(1):28–34. doi:10.1001/archinte.1956.00250250034005