Related Experiment Video
Updated: May 23, 2026
Dried Blood Spots - Preparing and Processing for Use in Immunoassays and in Molecular Techniques
Published on: March 13, 2015
Long-term stability of biochemical markers in pediatric serum specimens stored at -80 °C: a CALIPER Substudy
Davor Brinc1, Man Khun Chan, Allison A Venner
1Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
Insights
Pediatric serum analytes are stable for up to 13 months at -80°C, except for parathyroid hormone (PTH). This finding supports long-term storage for reference interval determination in children.
Area of Science:
- Clinical Chemistry
- Pediatric Endocrinology
- Laboratory Medicine
Background:
- Pediatric serum samples are stored long-term at -80°C for the CALIPER project.
- Understanding analyte stability is crucial for accurate reference interval determination.
Purpose of the Study:
- To assess the stability of chemistry, protein, and hormone analytes in pediatric serum stored at -80°C for up to 13 months.
- To evaluate the impact of long-term frozen storage on various biochemical markers.
Main Methods:
- Pooled pediatric serum samples were stored at -80°C for 10-13 months.
- 57 biochemical markers were analyzed monthly using VITROS, COBAS, and IMMULITE platforms.
- Analyte values were compared to baseline, with consideration for assay variability and freeze-thaw cycles.
Main Results:
- Most analytes demonstrated stability with no significant time-dependent changes over 13 months.
- Parathyroid hormone (PTH) showed a decline of up to 27.2% after 10 months, primarily within the first 2 months.
- Observed variability in other analytes was largely attributed to assay imprecision rather than degradation.
Conclusions:
- The majority of pediatric serum analytes are stable for up to 13 months when stored at -80°C.
- Immediate testing is not required for most analytes, facilitating reference interval studies.
- Parathyroid hormone (PTH) stability requires further investigation or careful consideration during long-term storage.
Objectives:
Pediatric serum samples collected from healthy children in the CALIPER (Canadian Laboratory Initiative in Pediatric Reference Interval) project are stored at -80 °C for various periods of time. This study aimed to determine the stability of chemistry, protein, and hormone analytes under these conditions.
Design And Methods:
Serum samples collected from children of 0-18 years of age attending outpatient clinics were pooled into a single pool or into age-group specific pools. Following baseline measurement, each pool was aliquoted and kept frozen at -80 °C until analysis. Samples were analyzed for 57 biochemical markers at monthly intervals over a 10-13 month period and each aliquot was subject to one freeze-thaw cycle before analysis. The analysis was performed on VITROS Chemistry System, COBAS INTEGRA 400 Plus and IMMULITE 2500. Values obtained at monthly intervals were compared to baseline measurements and examined for trends over time.
Results:
A majority of analytes measured in this study showed no significant time-dependent change relative to baseline or trend over time after up to 13 months of storage. PTH showed up to 27.2% decline after 10 months of storage with most of the decline evident after 2 months. Most analytes showed variability over time, which is thought to reflect assay variability rather than changes in analyte stability.
Conclusions:
The study shows stability for a majority of analytes stored in serum at -80 °C after up to 13 months of storage. Samples do not require immediate testing for reference interval determination for the selected analytes with possible exception of PTH.
