Glycolytic chain intermediary metabolism, glycerol and glycerophospholipid formation and the citric acid cycle. Simplified diagram of the intermediary metabolism of the glycolytic chain and its relation to the formation of glycerol and glycerophospholipids and to the citric acid cycle. Underlined metabolites are measured at the bedside with enzymatic techniques. Reference levels for normal human brain (during wakefulness) are presented . F-1,6-DP, fructose-1,6-diposphate; DHAP, dihydroxyacetone-phosphate; GA-3P, glyceraldehyde-3-phosphate; G-3-P, glycerol-3-phosphate; FFA, free fatty acids; La/py, lactate/pyruvate; a-KG, α-ketoglutarate.