Blood glucose level
Urinalysis
If ketones: adrenal or GH deficiency, inborn errors of metabolism
If no ketones: Hyperinsulinemia, fatty acid oxidation defects
If ketones: adrenal or GH deficiency, inborn errors of metabolism
If no ketones: Hyperinsulinemia, fatty acid oxidation defects
Blood glucose <45 in symptomatic neonate
Blood glucose <35 in asymptomatic neonate
Non-neonatal hypoglycemia 
Critical Illness
Neonatal hypoglycemia
Sepsis
Neonatal abstinence syndrome
Organ Failure
Neonatal jaundice
Hepatic failure