Table 2 Summary of serum metabolites quantified by LC-MS/MS, with reference values for healthy and uraemic blood

Neopterin^a

nM

81.2 ± 38.2 [42.4–224.6]

5.5 ± 2.0^c

8.5 ± 4.4^d

329.1 ± 42.7 (max)^c

172 ± 88.0^e

Cortisol

nM

212.9 ± 75.8 [91.4–468.7]

320 ± 190^f

n/a

Tryptophan

μM

27.8 ± 7.9 [10.0–48.5]

54.5 ± 9.7^f

31.2 ± 7.4^g

62.8 ± 9.3^d

17.3 ± 9.7^g

28.6 ± 8.8^e

Serotonin (5-HT)

nM

317.6 ± 221.2 [33.3–825.2]

740 ± 280^f,h

n/a

5-OH IAA

nM

262.6 ± 143.1 [114.2–704.6]

51.6 ± 6.8^f

n/a

Kynurenine^b

μM

3.02 ± 0.91 [1.46–5.32]

1.6 ± 0.1^f

1.6 ± 0.9^g

2.5 ± 0.7^d

3.3 ± 0.9ⁱ

2.7 ± 1.4^g

4.46 ± 2.5^e

Kynurenic acid^b

nM

557.3 ± 336.8 [168.4–1349.0]

30 ± 7^c,f

28.6 ± 17.1^g

800 ± 400 (max)^c,f

336.1 ± 72.6^g

Quinolinic acid^b

μM

1.72 ± 1.07 [0.52–4.97]

0.6 ± 0.3ⁱ

0.26 ± 0.1^g

9.0 ± 5.4ⁱ

7.9 ± 2.8^g

Xanthurenic acid

nM

417.5 ± 102.8 [207.9–637.2]

21.9 ± 0.98^f

170.1 ± 60.0^f

Quinaldic acid

nM

264.1 ± 164.1 [90.4–671.0]

n/a

n/a

3-OH Anthranilic acid

nM

50.8 ± 16.7 [26.5–95.8]

79 [15.0–209.0]^f

n/a

Indoxyl sulfate^b

μM

33.2 ± 33.9 [3.24–133.3]

2.5 ± 1.4^c

108.4 ± 61.0^c

IAA^b

μM

4.9 ± 4.0 [1.3–20.9]

2.9 ± 1.7^c

11.6 ± 2.2^c