Table 2.

Serum concentrations of amino acids between healthy controls and MDD patients

Amino acids	MDD patients (n = 247)		Healthy controls (n = 248)
(μmol/L)	Median	Q1-Q3	Median	Q1-Q3	p value
Alanine	233	202–492	238	203–502	0.065
Arginine	65.42	37.5–107	70.3	22.3–144	0.725
Aspartic acid	4.56	2.21–7.03	5.1	2.32–8.03	0.479
Cysteine	154	91.4–222	157	84.6–217	0.134
Glutamic acid	56.7	37.43–78.5	52.5	29.45–103	0.456
Glycine	205	114–476	210	104–464	0.107
Histidine	70.32	26.47–105	70.5	25.32-140	0.358
Isoleucine	51.3	41.94–80.7	53.6	37.43–99.4	0.212
Leucine	101	91.4–130	104	88.6–150	0.127
Lysine	159	92.1–305	157	90.3–290	0.837
Methionine	22.2	13.54–33.8	22.54	15.43–39.89	0.004a
Phenylalanine	64.8	54.41–93.73	69.7	53.58–115	< 0.001b
Proline	147	69.59–333	159	67.82–357	0.263
Serine	109	59.63–175	104	64.45–190	0.927
Threonine	128	62.52–210	136	65.73–206	0.088
Tryptophan	47.52	33.84–76.6	52.26	36.81–98.17	< 0.001c
Tyrosine	58.28	31.16–81.43	60.53	34.42–109	0.011d
Valine	196	156–311	189	149–309	0.752

p values from Mann-Whitney U test, p is significant at the 0.05 level, ^a Bonferroni-corrected p value < 0.05: patients < controls (p = 0.007), ^b Bonferroni-corrected p value < 0.05: patients < controls (p < 0.001), ^c Bonferroni-corrected p value < 0.05: patients < controls (p < 0.001), ^d Bonferroni-corrected p value < 0.05: patients < controls (p = 0.018)

Q1 lower quartile, Q3 upper quartile