Determination of in vitro stability of routine haematinics tests using EFLM standards and the CRESS checklist.

Background: Laboratories should be aware of the stability of the analytes they are testing in order to avoid incorrect reporting and patient management. Stability studies are difficult to interpret and reproduce, with little guidance on how to determine appropriate clinical cut off values. Here we describe a standardised approach to determining stability for routine haematinics tests using published EFLM guidelines.

Methods: The haematinics panel at UHNM contains vitamin B12, folate, ferritin, iron and transferrin. Blood tubes included were serum separator tubes, gel-free serum and lithium-heparin plasma. Conditions tested were room temperature, 2-8°C and -20°C. For each condition and tube, three samples were analysed in duplicate at 0, 24, 48, 72, 96 and 120 h using the Siemens Atellica platform.

Results: The percentage difference was calculated for each respective blood tube and storage condition, in addition to individual analyte maximum permissible instability scores. The majority of analytes for all blood tubes were stable for 5 days or more when stored at 4-8°C and -20°C. Ferritin (excluding gel-free), iron and transferrin further showed stability >5 days when stored at room temperature. However, vitamin B12 and folate demonstrated poor stability data for all tube types tested.

Conclusions: Here we describe a stability study for the haematinics panel on the Siemens Atellica platform using the standardised EFLM Checklist for Reporting Stability Studies (CRESS). The checklist was used in order to promote a standardised and transferable scientific approach to what has previously been lacking in the literature when performing stability experiments.