Diagnostic testing for persistent neonatal hypoglycemia

Initial diagnostic testing for persistent neonatal hypoglycemia (low glucose concentrations that persist beyond 48 hours of life) differentiates major etiologic categories of hypoglycemia based on laboratory testing (bicarbonate, beta-hydroxybutyrate, and free fatty acid) from a critical sample (obtained when the plasma glucose level is <50 mg/dL [2.8 mmol/L]). Additional specific testing (eg, plasma insulin, C-peptide, and carnitine and acyl-carnitine levels) using a critical sample is used to confirm the diagnosis of the underlying cause of hypoglycemia.