Table 1.
Summary of previous studies about 25‐OH VitD stability
| Publication | No. of samples | Storage Temp. | Analyzer | Type of Investigation | Tube type | Period | Outcome |
|---|---|---|---|---|---|---|---|
| Wielders et al, 20096 | 8 |
‐20°C, Dark 6°C Dark RT Bench RT |
Cobas E601 (Roche) | Temperature and freeze‐thawing cycles | Plain (serum) | Up to 2 mo | Frozen and unfrozen serum samples are reliable for analysis up to 3 d. No effect of light exposure or freeze‐thawing cycles on 25‐OH VitD levels. |
| Antoniucci, D. M et al, 2005.88 | 20 |
‐70°C RT |
RIA (DiaSorin) | Freeze‐thawing cycles | Plain (serum) | 3 d | After thawing and refreezing up to four times 25‐OH VitD results are still reliable. |
| Hayden Y et al, 20157 | 19 | ‐20°C | Cobas E602 | Storage, temperature, and sample type | SST (serum) | 144 d | 25‐OH VitD can be stored in the primary SST at –20°C without statistically significant change. |
| Bozkurt et., 201813 | 153 |
RT 2‐8°C ‐20°C ‐40°C |
IDS‐ISYS | Temperature and storage time | SST (serum) | 3 mo | There was no significant statistical difference in 25‐OH VitD level when they compared with first day sample level. |
| Chu‐Ling Yu 201014 | 20 |
RT, 2‐8°C |
Liaison (DiaSorin) and RIA | Delay in separation, sample type, and storage time | Plain (serum), EDTA (plasma), Heparin (plasma) | NA | No need for immediate analysis of blood samples after collection or for the choice of a tube type. The 25‐OH VitD in heparinized plasma may be higher than in serum or EDTA plasma |
| Ayfer Colak et al, 201315 | 15 |
RT 2‐8°C ‐20°C ‐80°C |
Cobas E 411 | Storage conditions and sample type | SST (serum) and EDTA (plasma) | 3 mo | There is no statistically significant difference between serum and plasma 25‐OH VitD at different storage conditions. |
| Borai A., 20168 | 50 | −80°C | HPLC, Architect (Abbott), and Liaison (Diasorin) | Sample type | SST (serum) and Plain (serum) | 6 mo | The gel in SST does not interfere with the measurement of 25‐OH Vit D. |
Immunoassay principles: Cobas, electrochemiluminescence; RIA, radioimmunoassay; IDS‐ISYS; chemiluminescent; Architect, chemiluminescent; Liaison, chemiluminescent.
Abbreviations: RT, room temperature; SST, serum separator tube, HPLC, high pressure liquid chromatography.