Pediatric emergency medicine trisk 2431 2431

Fatty acid oxidation
defects

primary respiratory alkalosis in the absence of toxic
ingestion
Must be free-flow venous (no tourniquet) or arterial.
Arterial preferred because skeletal muscle releases
ammonia, ice sample immediately, assay promptly
Newborns 90–150 μg/dL, children 40–120 μg/dL,
adults 18–54 μg/dL
(www.pediatriccareonline.org/pco/ub/view/Pediatricdrug-Lookup/153930/0/Normal-Laboratory-Valuesfor-Children )
Normal <100 μg/dL, neonate <80 μg/dL>1 mo
False positives—valproic acid
Obtain if vomiting, jaundice, and/or hepatomegaly
Hyperbilirubinemia predominantly conjugated, except
galactosemia first few days may be unconjugated

Liver function tests Hyperbilirubinemia
(serum)
Aminoacidopathies
Bilirubin
(tyrosinemia)
Transaminases
Carbohydrate
intolerance disorders
Clotting factors
Elevated transaminases
Aminoacidopathies
Organic acidemias
Urea cycle defects
Fatty acid oxidation

defects
Carbohydrate
intolerance disorders
Carbohydrate
production/utilization
disorders
Lysosomal storage
disorders
Mitochondrial disorders
Peroxisomal disorders
Muscle function
Abnormal muscle
Obtain if muscle weakness, tenderness, cramping,
tests (serum)
enzymes
atrophy, exercise intolerance
Lactate
Carbohydrate
Carnitine deficiency due to carnitine transport
dehydrogenase
production/utilization
disorders or secondary to organic acidemias, fatty
disorders
acid oxidation defects
Aldolase
Fatty
acid
oxidation
Creatine kinase
defects

Mitochondrial disorders
Urine
Reducing
substances
(Clinitest)

Aminoacidopathies
(tyrosinemia,
alkaptonuria)
Carbohydrate intolerance
disorders

Clinitest positive for reducing substances and dipstick
negative for glucose (glucose oxidase reaction)
False positives—penicillins, salicylates, ascorbic acid,
drugs excreted as glucuronides