RT Book, Section A1 Saudubray, Jean-Marie A2 Rudolph, Colin D. A2 Rudolph, Abraham M. A2 Lister, George E. A2 First, Lewis R. A2 Gershon, Anne A. SR Print(0) ID 6725849 T1 Chapter 149. Vitamin B6 and Vitamin B1 Responsive Disorders T2 Rudolph's Pediatrics, 22e YR 2011 FD 2011 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-149723-7 LK accesspediatrics.mhmedical.com/content.aspx?aid=6725849 RD 2024/03/29 AB Thiamine has long been recognized as an essential component. Its minimal essential requirement is about 0.5 mg/1000 Kcal, which is usually covered by a normal, well-balanced diet. However, requirements are variable and increase in parallel with carbohydrate intake, during pregnancy, lactation, hypermetabolic states, and in infants. Thiamine acts under its phosphorylated form, thiamine pyrophosphate (TPP), which is the coenzyme of pyruvate decarboxylase in the pyruvate dehydrogenase complex, α-ketoglutarate dehydrogenase, and oxidative decarboxylation of the three-branched chain alpha-keto acids. It is also the coenzyme of the transketolase in the pentose phosphate pathway. Being placed at these highly regulated enzymatic steps, thiamine plays a crucial role in carbohydrate metabolism and in the metabolic switch from the fed to the fasting state. Acute thiamine deficiency states (as in total parenteral nutrition without thiamine supplement) are life-threatening emergencies and present as cardiac failure, Gayet-Wernicke encephalopathy, or lactic acidosis.1,2