title: Evaluation of fasts for investigating hypoglycaemia or suspected metabolic disease.
abstract: OBJECTIVE
  To assess the value and safety of fasts for investigating hypoglycaemia or suspected metabolic disease.
  
  
  METHODS
  Review of all diagnostic fasts performed over a 2.5 year period.
  
  
  METHODS
  The neonatal intensive care unit and programmed investigation unit at a tertiary referral centre for endocrinology and metabolic disease.
  
  
  RESULTS
  138 diagnostic fasts were performed during the study period. Hypoglycaemia (< 2.6 mmol/l) occurred in 54 cases but in only four did the blood glucose concentration fall below 1.5 mmol/l. One patient became unwell as a result of a fast, but prompt treatment averted any sequelae. Specific endocrine or metabolic defects were identified in 30 cases, the most common being hyperinsulinism and beta-oxidation defects.
  
  
  CONCLUSIONS
  Fasting is safe if conducted on an experienced unit with appropriate guidelines. It continues to provide useful information for diagnosis and management, particularly in cases of hyperinsulinism. Diagnoses should, however, be established by lower risk procedures whenever possible. Thus specimens for metabolic and endocrine studies should be obtained during the presenting episode and blood acylcarnitine species should be analysed prior to fasting.
authors.affiliation: London.
authors.forename: A A
authors.initials: AA
authors.lastname: Morris
authors.forename: A
authors.initials: A
authors.lastname: Thekekara
authors.forename: Z
authors.initials: Z
authors.lastname: Wilks
authors.forename: P T
authors.initials: PT
authors.lastname: Clayton
authors.forename: J V
authors.initials: JV
authors.lastname: Leonard
authors.forename: A
authors.initials: A
authors.lastname: Aynsley-Green
mesh_terms: D020155:3-Hydroxybutyric Acid; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D005069:Evaluation Studies as Topic; D005215:Fasting / Q000009:adverse effects / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006801:Humans; D006885:Hydroxybutyrates / Q000097:blood; D006946:Hyperinsulinism / Q000175:diagnosis; D007003:Hypoglycemia / Q000209:etiology*; D007223:Infant; D007231:Infant, Newborn; D008659:Metabolic Diseases / Q000175:diagnosis*; D010084:Oxidation-Reduction
chemical_list: D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D006885:Hydroxybutyrates; D020155:3-Hydroxybutyric Acid