Mitchell G A, Kassovska-Bratinova S, Boukaftane Y, Robert M F, Wang S P, Ashmarina L, Lambert M, Lapierre P, Potier E
Service de génétique médicale, Hôpital Ste-Justine, Montréal, Québec.
Clin Invest Med. 1995 Jun;18(3):193-216.
Ketone bodies are produced in the liver, mainly from the oxidation of fatty acids, and are exported to peripheral tissues for use as an energy source. They are particularly important for the brain, which has no other substantial non-glucose-derived energy source. The 2 main ketone bodies are 3-hydroxybutyrate (3HB) and acetoacetate (AcAc). Biochemically, abnormalities of ketone body metabolism can present in 3 fashions: ketosis, hypoketotic hypoglycemia, and abnormalities of the 3HB/AcAc ratio. Normally, the presence of ketosis implies 2 things: that lipid energy metabolism has been activated and that the entire pathway of lipid degradation is intact. In rare patients, ketosis reflects an inability to utilize ketone bodies. Ketosis is normal during fasting, after prolonged exercise, and when a high-fat diet is consumed. During the neonatal period, infancy and pregnancy, times at which lipid energy metabolism is particularly active, ketosis develops readily. Pathologic causes of ketosis include diabetes, ketotic hypoglycemia of childhood, corticosteroid or growth hormone deficiency, intoxication with alcohol or salicylates, and several inborn errors of metabolism. The absence of ketosis in a patient with hypoglycemia is abnormal and suggests the diagnosis of either hyperinsulinism or an inborn error of fat energy metabolism. An abnormal elevation of the 3HB/AcAc ratio usually implies a non-oxidized state of the hepatocyte mitochondrial matrix resulting from hypoxia-ischemia or other causes. We summarize the differential diagnosis of abnormalities of ketone body metabolism, as well as pertinent recent advances in research.
酮体在肝脏中产生，主要来自脂肪酸的氧化，并被输送到外周组织用作能源。它们对大脑尤为重要，因为大脑没有其他重要的非葡萄糖衍生能源。两种主要的酮体是3-羟基丁酸（3HB）和乙酰乙酸（AcAc）。在生物化学方面，酮体代谢异常可表现为三种形式：酮血症、低酮性低血糖症以及3HB/AcAc比值异常。正常情况下，酮血症意味着两件事：脂质能量代谢已被激活，并且脂质降解的整个途径是完整的。在罕见的患者中，酮血症反映了无法利用酮体。禁食期间、长时间运动后以及食用高脂肪饮食时，酮血症是正常的。在新生儿期、婴儿期和妊娠期，脂质能量代谢特别活跃，容易发生酮血症。酮血症的病理原因包括糖尿病、儿童酮症性低血糖症、皮质类固醇或生长激素缺乏、酒精或水杨酸盐中毒以及几种先天性代谢缺陷。低血糖患者不存在酮血症是异常的，提示诊断为高胰岛素血症或脂肪能量代谢的先天性缺陷。3HB/AcAc比值异常升高通常意味着由于缺氧缺血或其他原因导致肝细胞线粒体基质处于非氧化状态。我们总结了酮体代谢异常的鉴别诊断以及相关的最新研究进展。
