Table 2.

Analytical determinations necessary for diagnosis in patients with hyperammonaemia.

Samples/Determinations	Considerations
Urgently processed samples
Ammonia	Careful extraction: no compression and through a large-calibre route. Keep the tube cold. Process within 1 h.
Ketone bodies	Using a blood reflective device and/or urine test strip.
Blood gases and anion gap	0.3 mL arterial or venous blood
Lactate	Careful extraction: no compression and through a large-calibre route.
Urgent biochemistry profile	Glycaemia, uric acid, urea, creatinine, total proteins, AST, ALT, gamma-glutamyltransferase, creatine kinase, sodium, potassium, chloride, calcium.
Other	Hemogram, coagulation profile, C-reactive protein and procalcitonin
Samples obtained in the acute phase and sent to a specialized laboratory as soon as possible
Blood aminogram and acylcarnitines	Serum or plasma samples (separate from whole blood). Liquid samples might need refrigeration or freezing for their conservation. Dried blood samples when it is not possible to obtain or adequately process liquid samples. Must differentiate into isolated peaks: glutamate, glutamine, alanine, citrulline, arginosuccinate, cystine, lysine and arginine.
Urine aminogram, orotic acid and organic acids	2–10 mL of the first urine obtained. Liquid samples might need refrigeration or freezing for their conservation. Dried blood samples when it is not possible to obtain liquid samples.
Hormone determination (insulin, C peptide and growth hormone)	If concomitant hypoglycaemia.
Bacterial cultures (blood, urine)	To rule out possible triggering infection.
Samples that can be obtained later but might be considered in an acute phase in cases with bad prognosis
Genetic testing samples	Preferably whole blood samples. Dried blood samples when it is not possible to obtain or adequately process liquid samples.

ALT, alanine transaminase; AST, aspartate transaminase.