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Human biomarkers for measuring potassium intake and status

About 80-90% of dietary potassium is excreted in the urine, the remaining being lost via faeces and sweat (3). Losses in sweat can increase when exposed to extreme heat conditions or a high sweat production due to intense physical activity, however acclimatisation to these conditions by the body is rapid and supplementation is rarely needed (4).

Note: the following methods detail recommendations for population biomarker assessment and are not suitable for use to assess individuals or in an individual clinical setting.


Quality control and technical assistance

Quality Control


ICP-MS and ISE: Standard Reference Materials (SRM) are available from the National Institute of Standards and Technology (NIST): SRM 2670a Toxic elements in urine (freeze-dried), level 1 (37.2 mmol/L) and level (41.0 mmol/L). See the method link on page 3 for more details.

To order SRM from NIST see this page.

ISE: CLINIQA standards used in the CDC NHANES method are available via this link.


The analysis of potassium may be biased by day-to-day intra-individual variations in potassium and in fluid intake, physical activity, the environment and medication use, including the use of diuretics. Potassium is also lost in faeces and sweat, though in temperate climates this factor is likely negligible(7), though seasonal variability could be considered in countries with appreciable summer-winter temperature differences.


Room temperature: Potassium is stable in urine for ≤ 14 days at 15-25 °C (17), though this is not recommended due to bacterial growth in the urine, and operator comfort during analysis.
Frozen: Potassium is stable indefinitely if stored frozen.
Freeze-thaw cycles: Up to 6 freeze-thaw cycles at -80 °C and up to 5 cycles at -20 °C did not affect potassium concentrations in patients with kidney disease (18).

We advise OpeN-Global users to consult relative SOPs for other biomarker analyses to be conducted in the collected urine samples to ensure all stability restrictions are considered.


Laboratory accreditation

For details on laboratory accreditation, validation or proficiency testing schemes, please see the OpeN-Global page on Laboratory accreditation.

Technical assistance

For technical assistance and advice on sodium assessment, contact or write to
Nutritional Biomarker Laboratory, University of Cambridge, UK. Email: