Serum and plasma determination of angiogenic and anti-angiogenic factors yield different results: The need for standardization in clinical practice

Figures & data

Table I.  Demographic and clinical characteristics of the study population.

	Normal pregnancy (n = 70)	Preeclampsia (n = 34)
Maternal age (years)	25.5 (15–39)	22.5 (18–38)
Pre-pregnancy BMI (kg/m^2)	23.5 (17.1–37.4)	25.7 (18.6–36.3)
Nulliparity (%)	25.7 (18/70)	64.7 (22/34)
Systolic blood pressure (mmHg)	120 (110–137)	160 (140–220)
Diastolic blood pressure (mmHg)	80 (65–88)	100 (90–150)
Gestational age at delivery (weeks)	39.4 (37–41.4)	36.4 (28–41)
Birth weight (g)	3400 (2770–4090)	2400 (830–4580)
Gestational age at maternal plasma/serum collection (weeks)	28.9 (6.1–40)	36.1 (27.6–40.9)
Early-onset preeclampsia (%)	–	38.2 (13/34)
SGA (%)	–	26.5 (9/34)

The results are expressed as percentage (proportion) or median (range).

BMI, body mass index; Early-onset preeclampsia, preeclampsia diagnosed <34 weeks of gestation; SGA, small-for-gestational age.

Table II.  Comparison of the maternal plasma and serum concentrations of sVEGFR-1, sVEGFR-2, PlGF and sEng in patients with a normal pregnancy.

Analyte	Plasma (n = 70)	Serum (n = 70)	p*
sVEGFR-1 (pg/ml)	2081.8 (264.8–19210.9)	2288.6 (277.7–15861.8)	<0.001
sVEGFR-2 (pg/ml)	9161.7 (6201.1–13817.8)	10231.4 (6379.4–16168)	<0.001
PlGF (pg/ml)	189.2 (6.8–1896.3)	197.5 (6.8–1841.8)	0.1
sEng (ng/ml)	8.6 (4.5–38.4)	8.4 (4.7–44.9)	0.7

The results are expressed as median (range).

*Wilcoxon ranks test.

Table III.  Comparison of the maternal plasma and serum concentrations of sVEGFR-1, sVEGFR-2, PlGF and sEng in patients with a normal pregnancy in the first, second and third trimester.

Analyte	Plasma (n = 70)	Serum (n = 70)	p*
First trimester	n = 10	n = 10
sVEGFR-1 (pg/ml)	1403.7 (264.8–3259.1)	1699.6 (277.7–3568.9)	0.005
sVEGFR-2 (pg/ml)	10178.8 (6916.3–11100.4)	10708.6 (7183.5–11804.7)	0.04
PlGF (pg/ml)	27 (6.8–58.9)	29.2 (6.8–50.5)	0.5
sEng (ng/ml)	7.3 (6.4–12)	7.3 (5.8–11.3)	0.1
Second trimester	n = 22	n = 22
sVEGFR-1 (pg/ml)	1542.9 (386.0–4133.6)	1698.7 (512.2–4686.2)	<0.001
sVEGFR-2 (pg/ml)	8970.9 (6673.4–13787.5)	10192.9 (6469.5–13573.9)	<0.001
PlGF (pg/ml)	145.3 (26.1–1896.3)	157.3 (27.3–1841.8)	0.5
sEng (ng/ml)	6.5 (4.5–38.4)	6.6 (4.7–43.6)	0.6
Third trimester	n = 38	n = 38
sVEGFR-1 (pg/ml)	2793.3 (827.1–19210.9)	3083.3 (885–15861.8)	<0.001
sVEGFR-2 (pg/ml)	8996.4 (6201.1–13817.8)	9947.8 (3379.4–16168)	0.003
PlGF (pg/ml)	304.4 (39.9–1606.3)	292.1 (41.8–1540)	0.2
sEng (ng/ml)	10 (5.6–34.9)	10.1 (5.6–44.9)	1.0

The results are expressed as median (range).

*Wilcoxon ranks test.

Figure 1.  Paired comparisons of the maternal plasma and serum concentrations of: A, sVEGFR-1; B, sVEGFR-2; C, PlGF; D, sEng in patients with preeclampsia.

Table IV.  Comparison of the maternal plasma and serum concentrations of sVEGFR-1, sVEGFR-2, PlGF and sEng in patients with preeclampsia.

Analyte	Plasma (n = 34)	Serum (n = 34)	p*
sVEGFR-1 (pg/ml)	17747.7 (5557.8–58140.6)	18284.5 (5955.4–70199.1)	0.01
sVEGFR-2 (pg/ml)	6668 (3487.8–10399.1)	7298 (3746.4–10725.4)	<0.001
PlGF (pg/ml)	60.5 (6.8–250.5)	61.4 (6.8–289.9)	0.001
sEng (ng/ml)	35.9 (11.2–353.2)	39.1 (12–437.5)	0.005

The results are expressed as median (range).

*Wilcoxon ranks test.