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Stability of serum TSH concentration after non refrigerated storage
G Koliakos1, M Gaitatzi, P Grammaticos
1Department of Biological Chemistry, AHEPA General Hospital, Medical School Aristotle University of Thessaloniki, Greece.
Insights
Patient serum samples for thyrotropin (TSH) testing can be stored for up to four days at room temperature or 4°C. This finding avoids unnecessary protective measures, reducing costs and labor in routine diagnostics.
Area of Science:
- Clinical Chemistry
- Endocrinology
- Laboratory Medicine
Background:
- Serum sample storage conditions are often overemphasized, leading to increased costs and labor.
- Improper storage can result in the exclusion of valuable patient data from analyses.
- Understanding sample stability is crucial for efficient laboratory routines.
Purpose of the Study:
- To evaluate the impact of different storage temperatures on serum thyrotropin (TSH) concentration.
- To determine the stability of TSH in patient serum samples under various storage conditions.
- To provide evidence-based recommendations for serum sample storage in TSH testing.
Main Methods:
- Three pooled serum samples were tested for TSH concentration.
- Samples were stored for four days at -15°C (freezing), 4°C (refrigerated), and 18-22°C (room temperature).
- TSH levels were measured using a commercial assay in 22 replicates for each condition.
Main Results:
- Storage conditions resulted in less than 10% variation in measured TSH values.
- The observed variation did not exceed the accepted between-assay variability.
- TSH concentration remained stable across tested storage durations and temperatures.
Conclusions:
- Patient serum samples for TSH estimation are stable for up to four days when stored at 4°C.
- Serum samples for TSH testing can also be stored at room temperature for up to four days without significant accuracy loss.
- These findings support less stringent storage protocols, potentially reducing laboratory costs and workload.
Background:
The ignorance of how sensitive serum samples for defined assays may be, can lead to overprotecting measures. This attitude not only increases cost and labor in everyday routine but may be responsible for not evaluating series of measurements if performed in serum samples not well stored.
Methods:
Thyrotropin (TSH) concentration in serum was tested in three pooled samples drawn from various patients, before and after four days storage at freezing (-15 degrees C), low (4 degrees C), and room temperature (18-22 degrees C). TSH concentration was measured in each part, in 22 replicates using a commercial assay.
Results:
The variation of the measured values due to the storage conditions was less than 10%, not exceeding the accepted between assay variation.
Conclusions:
For the estimation of TSH concentration, patient serum samples may be stored up to four days at 4 degrees C or even at room temperature without significant loss of measurement accuracy.
