The fasting test in paediatrics: Application to the diagnosis of pathological hypo- and hyperketotic states

Abstract

A 24-h fasting test was performed in 48 control children, in 9 hypoketotic patients with inherited defects of fatty acid oxidation and in 2 hyperketotic patients with inherited defects of ketolysis. The control group was then divided into three age groups on the basis of different adaptation to fasting. Concentrations of blood glucose, lactate, free fatty acids (FFA), 3-hydroxybutyrate, acetoacetate and carnitine were measured after 15 h, 20 h and 24 h of fasting. Significant negative correlations were found in the control group between plasma total ketone bodies (KB) and plasma glucose (P less than 0.001), plasma carnitine (P less than 0.005) and the amplitude of glycaemic response to glucagon at the end of the fast (P less than 0.01). FFA/KB ratio and the product of final fasting values of glucose and ketones were useful to differentiate between hypoketotic or hyperketotic patients and normal subjects. In children with a suspected or definite hyperketotic or hypoketotic disorder, a fasting test must only be performed in healthy patients, in good nutritional condition with non-diagnostic basal biochemical investigations. Carefully supervised fasting should be continued sufficiently to allow ketogenesis and ketolysis to become activated.

Glycerol kinase deficiency: residual activity explained by reduced transcription and enzyme conformation

“…In an effort to estimate the duration of a safe fasting period, a diagnostic fasting test was performed at the age of 4 years. 12 After 24 h of fasting, blood glucose was 3.6 mmol/l (controls 2.8 -3.8 mmol/l), 13 and there was a moderate metabolic acidosis (pH 7.31; base excess À8.9 mEq/l) with an impressive ketonemia and ketonuria. Plasma 3-hydroxybutyrate concentration at the end of the fasting test was 5.8 mmol/l (controls 1.7 -3.2 mmol/l).…”

“…Plasma 3-hydroxybutyrate concentration at the end of the fasting test was 5.8 mmol/l (controls 1.7 -3.2 mmol/l). 13 The psychomotor development and growth were considered to be normal. Patient 3, a male newborn, was born at 34 weeks of gestation with a birth weight of 1950 g and severe asphyxia.…”

Normoglycemic Ketonemia as Biochemical Presentation in Ketotic Glycogen Storage Disease

“…Five out of twelve patients displayed a biochemical phenotype suggestive of a ketolysis defect (Bonnefont et al 1990). It was recently reported that especially GSD IX is an unappreciated cause of idiopathic ketotic hypoglycemia (Brown et al 2014).…”

“…Previously, supervised clinical fasting studies have played a central diagnostic role as an informative functional in vivo test (Bonnefont et al 1990), but nowadays these studies are considered obsolete. Moreover, fasting studies are relatively time-consuming, expensive, invasive, and potentially dangerous.…”

“…Supervised clinical fasting studies were performed as described elsewhere (Bonnefont et al 1990;Van Veen et al 2011), for either diagnostic or therapeutic reasons, i.e., to titrate dietary management. Most diagnostic studies were performed before 2003, when plasma acylcarnitine profiling became available in our laboratory.…”