Many factors drive the selection of indicators. Some of these factors relate to participants, for example the acceptability and feasibility of the collection methods. Others concern field work (the ease of specimen collection, processing, storage, and transportation) and laboratory issues such as equipment, training, reagents, and costs. All these factors must be considered during the planning stage of the survey.

This module provides information to guide the selection of appropriate and reliable biomarkers, types of specimens, and methods of collection and analysis applicable to large micronutrient surveys. For each micronutrient there is a discussion of: specimen collection and management, biomarker analysis, an approximate budget, and how to interpret results. Issues of quality control are described where appropriate. The recommended collection containers, processing, storage and transport conditions for different specimen types are summarized in Table 3.11 at the end of the module. Costs have been calculated based on prices known in 2019. Actual costs for analyses may differ greatly from one laboratory to another.

Advice about the most suitable indicators and methods change periodically. During the planning phase, it is advisable to review the latest recommendations and consult with appropriate experts. Review papers on micronutrient status assessment developed under the Biomarkers of Nutrition for Development (BOND) program are shown in Box 3.1.