Table 2.

Biomarkers of organic acidemias identified in urine by GC-MS analysis and reference values (mean; 2.5th–97.5th percentiles)

Metabolite	Premature infants <36 weeks (n = 24)	Term newborns >36 weeks (n = 75)	Children <5 years (n = 880)	Subjects 5–18 years (n = 511)	Adults (n = 60)
Isovalerylglutamic acid	n.d.	n.d.	n.d.	n.d.	n.d.
3-OH-propionic acid	4.21; 1–6	4.26; 0–11	4.65; 0–13	3.66; 0–11	2.19; 0–5
Tiglylglycine	n.d.	0.11; 0–1	0.30; 0–2	0.01; 0–2	0.01; 0–1
2-OH-isovaleric acid	1.00; 0–4	0.01; 0–0.41	0.01; 0–1	0.01; 0–3	0.01; 0–2
3-OH-isovaleric acid	0.68; 0–10	0.23; 0–4	2.00; 0–11	1.00; 0–8	0.01; 0–3
Methylmalonic acid	n.d.	2.00; 0–5	1.29; 0–5	1.00; 0–3	0.01; 0–2
Propionylglycine	n.d.	n.d.	n.d.	n.d.	n.d.
Isovalerylglycine	n.d.	n.d.	0.15; 0–1	0.01; 0–1	n.d.
2-keto-isovaleric acid	n.d.	n.d.	0.01; 0–0	0.01; 0–0	n.d.
2-keto-3-Me-valeric acid	n.d.	0.03; 0–1	0.04; 0–1	0.11; 0–2	0.01; 0–1
2-keto-isocaproic acid	n.d.	0.17; 0–1	0.20; 0–1	0.13; 0–1	0.1; 0–1
2-OH-isocaproic acid	n.d.	n.d.	n.d.	n.d.	n.d.
2-OH-3-Me-valeric acid	n.d.	n.d.	n.d.	n.d.	n.d.
2-Methylcitric acid	n.d.	n.d.	0.02; 0–0	0.01; 0–0	0.01; 0–0

Metabolites are quantified as mmol/mol creatinine. n.d., not detectable.