Ketotic hypoglycemia

Ketotic hypoglycemia is a medical term used in two ways: (1) broadly, to refer to any circumstance in which low blood glucose is accompanied by ketosis, and (2) in a much more restrictive way to refer to recurrent episodes of hypoglycemic symptoms with ketosis and, often, vomiting, in young children. The first usage refers to a pair of metabolic states (hypoglycemia plus ketosis) that can have many causes, while the second usage refers to a specific 'disease' called ketotic hypoglycemia. Ketotic hypoglycemia is a medical term used in two ways: (1) broadly, to refer to any circumstance in which low blood glucose is accompanied by ketosis, and (2) in a much more restrictive way to refer to recurrent episodes of hypoglycemic symptoms with ketosis and, often, vomiting, in young children. The first usage refers to a pair of metabolic states (hypoglycemia plus ketosis) that can have many causes, while the second usage refers to a specific 'disease' called ketotic hypoglycemia. Ketotic hypoglycemia more commonly refers to a common but mysterious 'disease' of recurrent hypoglycemic symptoms with ketosis in young children. The cause and the homogeneity of the condition remain uncertain, but a characteristic presentation, precipitating factors, diagnostic test results, treatment, and natural history can be described. It remains one of the more common causes of hypoglycemia in the age range. The typical patient with ketotic hypoglycemia is a young child between the ages of 10 months and 4 years. Episodes nearly always occur in the morning after an overnight fast, often one that is longer than usual. Symptoms include those of neuroglycopenia, ketosis, or both. The neuroglycopenic symptoms usually include lethargy and malaise, but may include unresponsiveness or seizures. The principal symptoms of ketosis are anorexia, abdominal discomfort, and nausea, sometimes progressing to vomiting. If severe, parents usually take the child to a local emergency department, where blood is drawn. The glucose is usually found to be between 35 and 60 mg/dl (1.8-3.1 mMol/L). The total CO2 is usually somewhat low as well, (14-19 mMol/L is typical), and if urine is obtained, high levels of ketones are discovered. Ketones can also be measured in the blood at the bedside (Medisense glucometer). Other routine tests are normal. If given intravenous fluids with saline and dextrose, the child improves dramatically and is usually restored to normal health within a few hours. These symptoms are normally seen because of the child being unadapted to using fat as energy, typically when the child's daily glucose intake might be too high (more than 50g/day for a child). This is also associated with fluctuant glycemia throughout the day. A first episode is usually attributed to a viral infection or acute gastroenteritis. However, in most of these children one or more additional episodes recur over next few years and become immediately recognizable to the parents. In mild cases, carbohydrates and a few hours of sleep will be enough to end the symptoms. Thus said, the required amount of carbohydrate intake of a child, as well as for an adult is close to 0, because the liver can supply the required glucose quantity needed for the body through gluconeogenesis. Precipitating factors, conditions that trigger an episode, may include extended fasting (e.g., missing supper the night before), a low carbohydrate intake the previous day (e.g., a hot dog without a bun), or stress such as a viral infection. Most children affected by ketotic hypoglycemia have a slender build, many with a weight percentile below height percentile, though without other evidence of malnutrition. Overweight children are rarely affected. Some of the subtypes of Glycogen storage disease show ketotic hypoglycemia after fasting periods. Especially Glycogen storage disease type IX can be a common cause for ketotic hypoglycemia, with the most common sub-type IXa mainly affecting boys. There are hundreds of causes of hypoglycemia. Normally, the defensive, physiological response to a falling blood glucose is reduction of insulin secretion to undetectable levels, and release of glucagon, adrenaline, and other counterregulatory hormones. This shift of hormones initiates glycogenolysis and gluconeogenesis in the liver, and lipolysis in adipose tissue. Lipids are metabolized to triglycerides, in turn to fatty acids, which are transformed in the mitochondria of liver and kidney cells to the ketone bodies— acetoacetate, beta-hydroxybutyrate, and acetone. Ketones can be used by the brain as an alternate fuel when glucose is scarce. A high level of ketones in the blood, ketosis, is thus a normal response to hypoglycemia in healthy people of all ages. The presence or absence of ketosis is therefore an important clue to the cause of hypoglycemia in an individual patient. Absence of ketosis ('nonketotic hypoglycemia') most often indicates excessive insulin as the cause of the hypoglycemia. Less commonly, it may indicate a fatty acid oxidation disorder.