Test	Significance	Examples of inborn errors of metabolism associated with abnormal values
Urine
Ketones	Sign of ketosis	Ketouria found in organic acidemias, hypoketotic hypoglycemia in fatty acid oxidation disorders
Organic acids	Elevated organic acids in urine especially when patient is in a fasting or catabolic state	Amino acidopathies, organic acidemias, fatty acid oxidation disorders
Blood
Electrolytes, creatine kinase, creatinine	Acid-base analysis	Anion gap in organic acidemias (i.e., methylmalonic acidemia and propionic acidemia)
Creatine kinase	Cardiomyopathy	Fatty acid oxidation disorders, organic acidemias, mitochondrial disorders, glycogen storage disorders
Coagulation studies, alanine aminotransferase, aspartate aminotransferase	Liver disease	Fatty acid oxidation disorders, tyrosinemia type I, mitochondrial defects, hereditary fructose intolerance
Glucose	Hypoglycemia	Glycogen storage diseases and fatty acid oxidation disorders
Ammonia	Elevated levels cause encephalopathy	Urea cycle disorders, organic acidemias
Arterial/venous gas (pH, bicarbonate, CO2)	pH, acid base analysis	Acidosis (organic acidemias), elevated pH (occasionally in urea cycle disorders)
Acylcarnitines	Quantifies carbon chains esterified to carnitine	Organic acidemias and fatty acid oxidation disorders
Amino acids	Elevated amino acidlevels	Maple syrup urine disease, phenylketonuria, tyrosinemia type 1, some urea cycle disorders, elevated glycine in organic acidemias
Lactate	Hypoxia and tissue perfusion problems	Mitochondrial disorders, pyruvate dehydrogenase or carboxylase deficiency, organic acidemias, glycogen storage diseases