Selenium metabolism to the trimethylselenonium ion (TMSe) varies markedly because of polymorphisms in the indolethylamine N-methyltransferase gene.

Background: Selenium is an essential element, but its metabolism in humans is not well characterized. A few small studies indicate that the trimethylselenonium ion (TMSe) is a common selenium metabolite in humans.

Objective: This study aimed to elucidate the human metabolism of selenium to TMSe.

Concurrent quantitative HPLC-mass spectrometry profiling of small selenium species in human serum and urine after ingestion of selenium supplements.

Selenium metabolic patterns in the human body originating from five distinct selenium dietary sources, selenate, selenite, selenomethionine (SeMet), methylselenocysteine (MeSeCys) and selenized yeast, were investigated by performing concurrent HPLC-mass spectrometric analysis of human serum and urine. Total selenium and selenium species time profiles were generated by sampling and analyzing serum and urine from volunteers treated with selenium supplements, up to 5 and 24h following ingestion, respectively. We found that an increase in total serum selenium levels, accompanied by elevated selenium urinary excretion, was the common pattern for all treatments, except for that of selenite supplementation.

Quantitative determination of small selenium species in human serum by HPLC/ICPMS following a protein-removal, pre-concentration procedure.

Protein precipitation was incorporated into a sample preparation method for the quantitative determination of small "non-protein" selenium species in human serum by high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC/ICPMS). The advantages of cleaner matrix and concomitant concentration of the small compounds result in quantification limits in the native serum at the sub-micrograms Se per litre level. Spiking experiments with methyl 2-acetamido-2-deoxy-1-seleno-β-D-galactopyranoside (selenosugar 1), trimethylselenonium ion, selenomethionine, methylselenocysteine (MeSeCys) and selenate yielded recoveries from 73% to 103%.