EVALUATION OF FASTS FOR INVESTIGATING HYPOGLYCEMIA OR SUSPECTED METABOLIC DISEASE

Aim-To assess the value and safety of fasts for investigating hypoglyc aemia or suspected metabolic disease. Study design-Review of all diagn ostic fasts performed over a 2.5 year period. Setting-The neonatal int ensive care unit and programmed investigation unit at a tertiary refer ral centre for endocrinology and metabolic disease. Results-138 diagno stic 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 re sult of a fast, but prompt treatment averted any sequelae. Specific en docrine or metabolic defects were identified in 30 cases, the most com mon being hyperinsulinism and beta-oxidation defects. Conclusions-Fast ing is safe if conducted on an experienced unit with appropriate guide lines. It continues to provide useful information for diagnosis and ma nagement, particularly in cases of hyperinsulinism. Diagnoses should, however, be established by lower risk procedures whenever possible. Th us specimens for metabolic and endocrine studies should be obtained du ring the presenting episode and blood acylcarnitine species should be analysed prior to fasting.