Emergency metabolic tests

When a patient is admitted with a possible inborn error of intermediary metabolism, the following samples are required for metabolic studies.

The vital specimen: consider catheterisation or bladder tap

Urine

at least 3 mL

  Random sample, frozen or on ice. No added preservative. and transport on dry ice

  For amino acid profile, organic acid profile, acylglycines, orotic acid etc.

Next two most important samples

Plasma

at least 1 mL

  Lithium Heparin (not EDTA). Contact your laboratory as the sample needs to be separated and spun down within 20 minutes, then frozen at -80 C and transport on dry ice.

  For acylcarnitines, carnitine, quantitative amino acids, very long chain fatty acids, etc.

Dried blood spots

at least 1 mL

  Whole blood Lithium Heparin (not EDTA). Spot onto all circles of 3 or 4 Guthrie cards or store at +4 C. Transport cards in a paper envelope, NOT A PLASTIC BAG. Transport whole blood on ice.

  For acylcarnitine profile, galactose-1-phosphate uridyltransferase screen, DNA/PCR etc.

If the patient is hypoglycaemic

Plasma

Add a request to your laboratory for free fatty acids, 3 hydroxybutyrate.

If the patient is to have a lumbar puncture

CSF

at least 250 µL

  Collected within 1 hour of the matching plasma sample. MUST be free of red cells. Freeze and store at -80 C and transport on dry ice.

  For quantitative amino acids, especially glycine or homocarnosine.