Ketosis is caused by

KETOSISNormally the rate of synthesis of ketone bodies by the liver is such that they can be easily metabolised by the extrahepatic tissues. Hence the blood level of ketone bodies is less than 1 mg/dl and only traces are excreted in urine (not detectable by usual tests).But when the rate of synthesis exceeds the ability of extrahepatic tissues to utilise them, there will be accumulation of ketone bodies in blood.This leads to ketonemia, excretion in urine (ketonuria) and smell of acetone in breath. All these three together constitute the condition known as ketosis.Causes for KetosisDiabetes Mellitus: Uncontrolled diabetes mellitus is the most common cause for ketosis. Even though glucose is in plenty, the deficiency of insulin causes accelerated lipolysis and more fatty acids are released into circulation. Oxidation of these fatty acids increases the acetyl CoA pool. Enhanced gluconeogenesis restricts the oxidation of acetyl CoA by TCA cycle since the availability of oxaloacetate is less.Starvation: In starvation, the dietary supply of glucose is decreased. Available oxaloacetate is channeled to gluconeogenesis. The increased rate of lipolysis is to provide alternate source of fuel. The excess acetyl CoA is conveed to ketone bodies. The high glucagon level ors ketogenesis. The brain derives 60-75% of energy from ketone bodies under conditions of prolonged starvation. Hyperemesis (vomiting) in early pregnancy may also lead to starvation-like condition and may lead to ketosis.Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 144