Selenomethionine (SeMet) is an important organic nutritional source of Se, but the uptake and metabolism of SeMet are poorly characterised in humans. Dynamic gamma camera images of the abdominal region were acquired from eight healthy young men after the ingestion of radioactive 75Se-l-SeMet (75Se-SeMet). Scanning started simultaneously to the ingestion of 75Se-SeMet and lasted 120 min. We generated time-activity curves from two-dimensional regions of interest in the stomach, small intestine and liver. During scanning, blood samples were collected at 10-min intervals to generate plasma time-activity curves. A four-compartment model, augmented with a delay between the liver and plasma, was fitted to individual participants’ data. The mean rate constant for 75Se-SeMet transport was 2·63 h–1 from the stomach to the small intestine, 13·2 h–1 from the small intestine to the liver, 0·261 h–1 from the liver to the plasma and 0·267 h–1 from the stomach to the plasma. The delay in the liver was 0·714 h. Gamma camera imaging provides data for use in compartmental modelling of 75Se-SeMet absorption and metabolism in humans. In clinical settings, the obtained rate constants and the delay in the liver may be useful variables for quantifying reduced intestinal absorption capacity or liver function.

Se metabolism in humans is not well characterised. Currently, the estimates of Se absorption, whole-body retention and excretion are being obtained from balance and tracer studies. In the present study, we used gamma camera imaging to evaluate the whole-body retention and distribution of radiolabelled selenomethionine (SeMet), the predominant form of Se present in foods. A total of eight healthy young men participated in the study. After consumption of a meal containing 4 MBq [75Se]l-SeMet ([75Se]SeMet), whole-body gamma camera scanning was performed for 45 min every hour over a 6 h period, every second hour for the next 18 h and once on each of the subsequent 6 d. Blood, urine and faecal samples were collected to determine the plasma content of [75Se]SeMet as well as its excretion in urine and faeces. Imaging showed that 87·9 (sd 3·3) % of the administered activity of [75Se]SeMet was retained within the body after 7 d. In contrast, the measured excretion in urine and faeces for the 7 d period was 8·2 (sd 1·1) % of the activity. Time–activity curves were generated for the whole body, stomach, liver, abdomen (other than the stomach and the liver), brain and femoral muscles. Gamma camera imaging allows for the assessment of the postprandial absorption of SeMet. This technique may also permit concurrent studies of organ turnover of SeMet.