Pediatric emergency medicine trisk 2435 2435

Test

Laboratory abnormality
metabolic diseases a

Indications, comments

Aminoacidopathies
Organic acidemias

Tandem mass spectrometry, requires
minimum 1 mL blood, 3 mL ideal b ,
heparin, or EDTA tube
Obtain if metabolic catastrophe, neurologic,
cardiac, GI/hepatic, musculoskeletal,
psychiatric symptoms suggestive of
possible IEM, metabolic acidosis, elevated
anion gap, hypoglycemia, inappropriate
ketonuria, hyperammonemia

Blood
Amino acids—
quantitative (plasma
or serum)

Urea cycle defects
Mitochondrial disorders

Acylcarnitine profile
(plasma or serum)

Organic acidemias
Fatty acid oxidation defects
Mitochondrial disorders
Primary carnitine deficiency

Lactate, pyruvate
Disorders of carbohydrate
(deproteinized blood)
utilization
Mitochondrial disorders

Carnitine deficiency may be due to primary
defect in carnitine or carnitine transporter,
or secondary due to organic acidemia or
fatty acid oxidation defect; can also occur
in normal children during dehydration
Free and total carnitine may also be helpful if
carnitine deficiency is suspected
Samples must be free flow, deproteinized at
bedside—1 mL into tubes with 2-mL
perchloric or trichloroacetic acid, transport
on ice
Evaluate lactate, pyruvate, and ratio
Lactate also increased in patient with
hypoxia, poor perfusion, sepsis

Urine
Organic acids

Aminoacidopathies

Organic acidemias
Fatty acid oxidation defects
Mitochondrial disorders
Peroxisomal disorders

Acylglycines

Organic acidemias
Fatty acid oxidation defects

Orotic acid

Urea cycle defects (ornithine
transcarbamylase
deficiency)

Urine best source for organic acids, minimum
2–5 mL, 10–20 mL ideal without
preservative c
Obtain if metabolic catastrophe, neurologic,
cardiac, GI/hepatic, musculoskeletal,
psychiatric, symptoms suggestive of
possible IEM, metabolic acidosis, elevated
anion gap, hypoglycemia, inappropriate
ketonuria, hyperammonemia
Should be performed only in conjunction
with serum or plasma carnitines, minimum
2–5 mL without preservative c
Send if hyperammonemia, minimum 1 mL
without preservative

Cerebrospinal fluid
Glucose, protein, lactate, Aminoacidopathies
pyruvate, glycine,
Organic acidemias
serine, alanine,

1–4 mL, freeze −20°C or −70°C