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Published on: August 2, 2017
Stability of first trimester placental growth factor in serum and whole blood
N J Cowans1, H Alfthan, U H Stenman
1Department of Clinical Biochemistry, King George Hospital, Goodmayes, Essex, UK.
Insights
Placental growth factor (PlGF) stability varies by storage. Serum PlGF is stable for 30 days refrigerated, but whole blood degrades quickly at room temperature or 30°C.
Area of Science:
- Biochemistry
- Clinical Chemistry
- Reproductive Medicine
Background:
- Placental growth factor (PlGF) is a potential first-trimester biomarker for pre-eclampsia detection.
- Assessing PlGF stability is crucial for its reliable use in clinical diagnostics.
Purpose of the Study:
- To evaluate the stability of PlGF in serum and whole blood under various storage conditions.
- To determine optimal sample handling protocols for PlGF-based pre-eclampsia screening.
Main Methods:
- Serum and whole blood samples were stored at different temperatures (refrigerated, room temperature, 30°C) for defined periods.
- Freeze-thaw cycle stability was assessed for serum samples.
- PlGF concentrations were measured using a DELFIA Xpress analyser.
Main Results:
- Serum PlGF remained stable for at least 30 days when refrigerated, and through six freeze-thaw cycles.
- PlGF in serum showed instability at room temperature (stable for 3.3 days) and 30°C (stable for 1 day).
- Whole blood PlGF exhibited significant instability, stable for only 19.4 hours at room temperature and 3.3 hours at 30°C.
Conclusions:
- Careful monitoring of sample handling is necessary for routine PlGF screening.
- No additional precautions are required for PlGF when integrated into existing first-trimester aneuploidy screening programs that include hCGβ.
Background:
Placental growth factor (PlGF) is a proposed first-trimester screening marker for pre-eclampsia. This study investigates the stability of PlGF in serum and whole blood at typical routine storage temperatures.
Methods:
Serum pools were stored at refrigerator temperature, room temperature or 30 °C for up to 30 days, or exposed to up to six freeze-thaw cycles. Whole blood was stored at room temperature or 30 °C for up to 6 days. PlGF was quantified using a DELFIA Xpress analyser.
Results:
Placental growth factor levels increased over time, seemingly because of the dissociation of PlGF bound to a soluble binding protein, sFlt-1. Increase was slow in serum at refrigerator temperature, remaining stable (less than 10% change from start point) for at least 30 days. At room temperature PlGF was stable for 3.3 days and at 30 °C for 1 day. Serum PlGF remained stable for at least six freeze-thaw cycles. In whole blood, instability was worse, being stable for only 19.4 h at room temperature and just 3.3 h at 30 °C.
Conclusion:
Routine screening of sample handling requires careful monitoring. However, no extra precautions need to be taken when PlGF is used for pre-eclampsia screening run alongside existing first trimester aneuploidy screening programs that include hCGβ.
