Serum placental growth factor: Pre-analytical stability, comparison of blood derivates and interference from biotin...

Placental growth factor (PlGF) is an increasingly applied biomarker in the early prediction of preeclampsia. To use PlGF clinically, preanalytical factors and biotin/hemolysis susceptibility must be validated, this forms the aim of this study.

We examined the stability of PlGF including precision, delayed centrifugation, comparability between serum and EDTA-plasma, pneumatic tube transportation, storage at room temperature, 5 °C, -80 °C and undergoing freeze-thaw cycles and further, exposure to biotin and hemolysis. Blood was obtained from pregnant women with a gestational age ≥ 11 weeks. PlGF was measured using a KRYPTOR GOLD analyzer. Stability was defined as the mean percentage difference (PD%) of maximum 10 % between the baseline and subsequent samples.

Five replicates of the control samples (31, 87 and 373 ng/L) and one patient pool (22 ng/L) showed a repeatability of 2.2 to 7.7 % and within-laboratory CV of 2.3 to 9.5 %. The mean PD% after delayed centrifugation for two, five and seven hours was maximum 5.2 %. The comparison of matrixes showed a good correlation with a mean PD% of 7.2 %. The pneumatic tube transportation resulted in a maximum PD% of 8.4 %. The storage and freeze thaw studies exhibited a maximum mean PD% of 7.9 %. The spiked samples with 500 ng/mL biotin or 287 mg/dL hemoglobin resulted in a maximal mean PD% of 4.2 %.

We found PlGF to be stable when exposed to a broad spectrum of pre-analytical conditions, across varying PlGF levels and after exposure to biotin or hemolysis.