TABLE 1.

Se metabolites idenfied from human urinary and serum.

Se metabolite	Monoisoto pic mass	Baseline abundance	Response	Ref
TMSe (trimethylselenoniu m ion)	124.987	-Trace in urine and serum. -Varied between TMSe producers (major) and non-TMSe producers (minor or non- detectable) in urine	-Increase as a minor urinary product after SeMet supplement -Increase moderately in urine after selenite supplement -Minor product in urine	[106, 180, 181]
Selenosugar 1 (methyl-2- acetamido-2-deoxy- 1-seleno-b-D- galactopyranoside)	299.027	-Small amount in urine and serum -Major metabolite in urine non-TMSe producers -Major urinary metabolite	-Increase to the major product after SeMet treatment -Respond strongly to SeMet treatment as the major metabolite	[102, 180, 181]
Selenosugar 3 (methyl-2-amino-2- deoxy-1-seleno-b-D- galactopyranoside)	257.0164	-Small amount in urine and serum -2nd major metabolite in non- TMSe producers -Major metabolite	-Increase to the 2nd major product after SeMet treatment -Increase moderately after selenite supplement	[106, 180, 181]
SeMet (selenomethionine)	196.9955	-Below detection limit in serum and urine	-Increase after L- SeMet supplement; - No response to other supplement	[180, 181]
SeMSC (Se-methyl- selenocysteine)	182.9799	-Expected but not detected	-Trace in serum. Increase in Se excreted in urine after supplementat ion with SeMSC	[182]
Selenite	127.9013	-Low amount in serum -Below detection limit in urine	-Unchanged in serum -Below detection limit in urine	[106, 180]
Selenate	143.8962	-Below detection limit in urine	-Increase moderately after selenite supplement in urine	[106]
Selenocystathionine	270.0119	-detected not quantified in the urine	-Increased in epithelial ovarian cancer	[183]
Selenocystine	335.9128	-detected and quantified in the serum	-decrease in cystic fibrosis patients compared to healthy controls	[184]