Table 2

Investigations for the diagnosis of an IEM

 First line investigations
 Full blood count
Urea and electrolytes
Anion gap
Blood gases
Liver function tests
Urine reducing substances
Urine ketones
CSF lactate
Second line investigations
Urine organic acids
Urine amino acids
Plasma uric acid
Plasma amino acids
Plasma carnitine and acylcarnitine profile
Galactosaemia screening tests (e.g. Beutler)
CSF amino acids
Third line or specialised investigations
Enzyme assays on skin fibroblasts or blood cells
DNA mutation analysis
Special metabolite assays (e.g. VLCFA, transferrin isoelectric focusing, etc)