Protocol - Selenium
The analytical method for serum selenium (Se) is based on inductively coupled plasma mass spectrometry (ICP-MS) using matrix-matched calibration standards. In this method, Se (isotope mass 78 and/or mass 80), and gallium (mass 69) are measured in serum by inductively coupled plasma dynamic reaction cell spectrometry using methane as reaction gas.
Another analytical method to quantify serum selenium (Se) is based on electrothermal atomic absorption (AA), which is commonly used to measure plasma Se and is more accessible for most researchers than ICP-MS. ICP-MS is required for Se-speciation and limited sample cases such as biopsies.
1. Specimen Collection, Storage, and Handling Procedures; Criteria for Specimen Rejection
A. Specimen should be collected in a Red-Top tube that is prescreened for trace metal contamination. Specimen-type serum, optimal amount of specimen required is 2-3 mL, minimum volume required for analysis is about 0.8 mL.
B. Specimens may reach and maintain ambient temperature during analysis. Stringent precautions should be taken to avoid external contamination by the metals to be determined.
C. The criteria for unacceptable specimens are either a low volume (<0.8 mL) or suspected contamination due to improper collection procedures or collection devices. In all cases, a second specimen should be requested.
D. Specimen characteristics that may compromise test results include contamination of serum by contact with dust, dirt, etc. from improper handling.
E. In general, handle specimens in ways that prevent microbial growth. Serum specimens should be transported and stored at 4°C. Once received, they can be frozen at -20°C or at -70°C until time for analysis. Portions of the sample that remain after analytical aliquots are withdrawn and should be refrozen at -20°C. Samples thawed and refrozen several times are not compromised. Dried blood spots are also suitable.
2. Detection Ranges Reference Ranges (Normal Values) adapted from National Committee for Clinical Laboratory Standards (NCCLS) 38A(3): Selenium
Protocol Name from Source:
2004 National Center for Environmental Health Laboratory Procedure Manual for Serum Selenium
Personnel and Training Required
Must complete safety training seminars prior to performing any work in the Lead Poisoning/Trace Elements Laboratory.
Highly specialized equipment is necessary to perform accurate selenium measurements.
|Specialized requirements for biospecimen collection||No|
|Average time of greater than 15 minutes in an unaffected individual||No|
Mode of Administration
Infant, Toddler, Child, Adolescent, Adult, Senior, Pregnancy
Strict adherence to quality control (QC) procedures outlined in the protocol text is recommended. Controls should be run at the beginning of the day, one control should be analyzed again after approximately each of 10 patient samples, and all QC controls are run at the end of each day. Agreement with certified or accepted QC values should be within the ±2 standard deviation limits.
This assay is sensitive enough to be used to rapidly screen serum specimens from subjects for elements of toxic and nutritional interest. The protocol is taken from the standard procedure used by the Centers for Disease Control and Prevention (CDC) Elemental Analysis Laboratory for the National Health Examination Survey (NHANES).
|Common Data Elements (CDE)||Person Serum Selenium Level Number||2946951||CDE Browser|
|Logical Observation Identifiers Names and Codes (LOINC)||PhenX - selenium protocol||62287-8||LOINC|
Process and Review
The Expert Review Panel #1 reviewed the measures in the Anthropometrics, Diabetes, Physical Activity and Physical Fitness, and Nutrition and Dietary Supplements domains.
Guidance from the ERP includes:
No significant changes to measure
Back-compatible: no changes to Data Dictionary
Previous version in Toolkit archive (link)
Centers for Disease Control and Prevention, Division of Laboratory Sciences, National Center for Environmental Health Laboratory Procedure Manual for Serum Selenium, August 24, 2004.
Lockitch, G., Fassett, J. D., Gerson, B., Nixon, D. E., Parsons, P. J., & Savory, J. (1997). Control of pre-analytical variation in trace element determinations; Approved guideline (NCCLS document C38-A). Wayne, PA: National Committee for Clinical Laboratory Standards.
Centers for Disease Control and Prevention, National Center for Health Statistics. National Health and Nutrition Examination Survey (NHANES) Overview 2007-2008.
Combs, G., Jr., & Gray, W. P. (1998). Chemo preventive agents: Selenium. Pharmacology and Therapeutics, 79, 179-192.
Jackson, I and Combs, GF. (2012) Selenium as a Cancer Preventive Agent in Selenium, Its Molecular Biology and Role in Human Health. Dolph L. Hatfield, Marla J. Berry, Vadim N. Gladyshev, Editors. Springer, New York pp 313-319.
McKenzie, R. C., Rafferty, T. S., & Beckett, G. J. (1998). Selenium: An essential element for immune function. Immunology Today, 19, 342-345.
Office of Dietary Supplements, National Institutes of Health Dietary Supplement Fact Sheet: Selenium.
Thomson, C. D. (2004). Assessment of requirements for selenium and adequacy of selenium status: A review. European Journal of Clinical Nutrition, 58, 391-402.
|Variable Name||Variable ID||Variable Description||Version||dbGaP Mapping|
|PX050901_Selenium_Collection_MicrogramsPerLiter||PX050901010100||Selenium Concentration in ug/L||4||N/A|
|PX050901_Selenium_Collection_MicroMolar||PX050901010200||Selenium Concentration in umol/L||4||N/A|
October 1, 2015
A measure to assess concentration (micrograms per liter or micromoles per liter) of serum selenium.
Selenium (Se) is important for antioxidant capacity and has cancer prevention properties.
Nutrition and Dietary Supplements, antioxidant, NHANES, NCCLS