Table 3.

Potential biomarkers, metabolic pathways, and metabolic tendencies of biomarkers from YDYHS to YYDS.

Number	Instrument	Metabolites	Metabolic pathway	Metabolic tendency
				YDYHS versus controls	YYDS versus controls	YYDS versus YDYHS
1	NMR	Betaine	Epinephrine biosynthesis	↑	↓	↓
2	NMR	Mevalonic acid	Cholesterol biosynthesis	↑	↓	↓
3	NMR	Corticosterone	Steroid hormone biosynthesis	↑	↓	↓
4	NMR	Beta-leucine	Valine, leucine, and isoleucine degradation	↑	↓	↓
5	NMR	Propionic acid	Cysteine and methionine metabolism	—	↓	↓
6	GC-MS	Methionine	Cysteine and methionine metabolism	↓	↓	↓
7	GC-MS	D-glucose	Tricarboxylic acid cycle	↑	↑	↓
8	GC-MS	Glycine	Glycine, serine, and threonine metabolism	↑	↓	↓
9	GC-MS	Tyrosine	Tyrosine metabolism	↑	—	↓
10	GC-MS	Malic acid	Fatty acid biosynthesis	↑	↓	↓