Assessment of biomarker selection in selenium-deficiency disease

Wildlife Medicine Department
Wildlife Resource College
Northeast Forestry University
26 He-xing Road
Harbin 150040
Heilongjiang Province
China
E-mail: wxlz1969{at}yahoo.com.cn or reptiles{at}21cn.com

Dear Sir:

Setting a standard for selenium status evaluation can be vexing. For example, in a recent article in the Journal, Xia et al (1) concluded that the use of glutathione peroxidase as an index of selenium status may not be appropriate. They found that full expression of selenoprotein P (SeP) requires a greater selenium dietary exposure than does full expression of plasma glutathione peroxidase activity. This implies that SeP is a better indicator of selenium nutritional status than is glutathione peroxidase (1). SeP is the transporter of selenium in serum (2, 3) and plays important roles in selenium tissue regulation (4-6). However, from the perspective of selenium-related disease assessments, even changes in SeP concentrations may not be useful. A low selenium status obtained with the use of glutathione peroxidase or SeP as indicators in clinical trials did not clearly predict Keshan disease in selenium-deficienct areas in China (7). Because SeP is more sensitive to selenium depletion than are other selenoproteins, it may be too sensitive for use as a standard. Turnover rates differ among selenoproteins (8, 9), which suggests that the regulating mechanisms also differ (10); in some tissues, the mechanisms of selenium use can be differentially sustained during dietary selenium depletion (11). Thus, evidence of selenium deficiency according to an arbitrary standard does not necessarily lead to a clinical prediction, even though the activity of a given selenium-containing enzyme may be reduced. Thus, the evaluation is less robust if it is based on only one criterion. Practical experience also showed that the assessment of selenium status should be carried out separately for different tissues (12). Adoption of SeP as the principal standard for selenium status evaluation does not adequately focus on the clinical specificities of different selenium-responsive diseases. In summary, biomarkers should be selected to match the characteristics of different selenium-responsive diseases.

ACKNOWLEDGMENTS

The author had no conflicts of interest.

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