Plasma or serum zinc
Plasma/serum zinc concentration reflects dietary zinc intake during the previous weeks, responds consistently to zinc supplementation, and reference data are available for most age and sex groups, making it an appropriate biomarker for use in research studies (e.g. to assess the response of a zinc supplementation intervention) and population health surveys alike.
Serum zinc concentration can be measured by atomic absorbance spectrometry (AAS), inductively couple plasma optical emission spectrometry (ICP-OES), and inductively coupled plasma mass spectrometry (ICP-MS) (7).
ICP-MS: For a method description, see: Thomas D. B. Lyon, Gordon S. Fell, Robert C. Hutton and Andrew N. Eaton. Evaluation of inductively coupled argon plasma mass spectrometry (ICP-MS) for simultaneous multi-element trace analysis in clinical chemistry. Journal of Analytical Atomic Spectrometry, 1988, 3 265-271.
For further methodological advice and guidance: see the Biomarkers of Nutrition for Development (BOND)—Zinc Review (7)and the IZiNCG Technical Brief no. 2: Assessing population zinc status with serum zinc concentration and no. 9: The value of measuring plasma or serum zinc concentrations in national surveys.
Confounding factors such as infection can lower serum zinc concentrations, leaving to overestimation of zinc deficiency(19). Furthermore, plasma zinc concentrations can be influenced by other food intake, time of day, sex, age, pregnancy, oral contraceptive use, severe stress, position of subject during blood drawing, and length of time subject‘s arm is occluded with a tourniquet (7). Cut-offs may vary accordingly. See the IZiNCG’s Technical Brief no. 2 and page on practical tips for zinc analysis, for advice on good blood collection techniques for zinc analysis.
Contamination: Zinc is present in serum and plasma only in very low concentrations. Thus, any contamination from external sources must be avoided as it can dramatically change the results. See the IZiNCG’s Technical Brief no. 2 and page on practical tips for zinc analysis.
Haemolysis of blood sample: See See the IZiNCG’s Technical Brief no. 6: How to deal with haemolysis for plasma/serum zinc analysis
See the section on Useful links, for details on how to keep in touch with IZiNCG and get regular updates on new publications.
IZiNCG recommends that when the prevalence of a low plasma/serum zinc concentration is > 20%, the risk of zinc deficiency is considered elevated and should be addressed through public health interventions to improve zinc status (20, 21).
Further advice on statistical analysis and suggested lower cut-offs can be found on the IZiNCG page on practical tips for zinc analysis
See the section on Useful links, for details on how to keep in touch with IZiNCG and get regular updates about new publications.
Other recommended markers of population zinc status
Prevalence of stunting:
Height- or length-for-age is the best-known functional outcome associated with the risk of zinc deficiency in populations. For population assessment, the advised indicator to use is the percentage of children under 5 years of age with length- or height-for age less than –2.0 SD below the age-specific median of the reference population.
The risk of zinc deficiency is considered elevated and of public health concern when the prevalence of low height- or length-for-age is greater than 20%.
For methods and advice, see:
IZiNCG resources available under Assessment of Stunting
WHO pages: Stunting in a nutshell
Assessment of dietary zinc intake:
Reliable methods have been developed to evaluate dietary zinc intakes and to assess the risk of inadequacy for individuals and population groups. As a result, vulnerable individuals can be identified for dietary counselling and at-risk subgroups in the population targeted for intervention programs.
For methods and advice, see IZiNCG technical brief no. 3 and further IZiNCG resources available under Assessment of Dietary Zinc Intakes
For further information, see the Institute of Medicine Food and Nutrition Board guidance on Dietary Reference Intakes: applications in dietary assessment, available at
Hair or nail zinc
Analysis of scalp hair and nail zinc is a potential biomarker of zinc status which may have advantages for use in LMIC settings due to the ease of sampling, stability of samples, and lack of need for a cold chain. Hair zinc is classified as a potential- and
nail zinc as an emerging- biomarker of zinc exposure by the BOND Zinc Expert Panel
(7). Currently, they are not recommended as
a single assessment indicator of zinc status. However, they are recommended for further development as more data are urgently needed to confirm their sensitivity and specificity to changes in zinc nutrition and
to establish reference limits or true cutoffs indicative of zinc deficiency.
For a method description, see the IZiNCG Technical Brief 8: Assessing population zinc exposure with hair or nail zinc.
Other methods include assessment of zinc-dependent proteins; oxidative stress and DNA integrity; zinc kinetics; taste acuity tests. OpeN-Global readers should consult the Biomarkers of Nutrition for Development (BOND)—Zinc Review or the IZiNCG Technical Briefs and the IZiNCG pages on Assessment of Zinc Status.
As described, when measuring plasma or serum zinc concentration, it is important to remember that zinc is present in only very low concentrations and contamination from external sources (i.e. inappropriate supplies and materials, the environment) is easy. It is therefore important to maintain strict quality control procedures when collecting, storing and processing samples for analysis. See the description and links above for more details.
Laboratory accreditation and technical assistance
For all questions on laboratory accreditation and validation schemes for zinc assessment, as well as technical queries, please see the OpeN-Global page on laboratory quality assessment and accreditation, or write to email@example.com or to IZiNCG.