Unit Converter
PlGF – Placental growth factor
(Key Angiogenic Biomarker for Preeclampsia Screening, Diagnosis & Placental Dysfunction)
Synonyms
- Placental Growth Factor
- PlGF
- Placenta-derived growth factor
- Angiogenic factor
- VEGF family member (VEGF-B)
Units of Measurement
- pg/mL
- pg/dL
- pg/100 mL
- pg%
- pg/L
- ng/L
Molecular Weight
~20–25 kDa (glycosylated dimeric protein)
Unit Conversions
Direct mass conversions
1 pg/mL=1000 pg/L1\ \text{pg/mL} = 1000\ \text{pg/L}1 pg/mL=1000 pg/L 1 pg/mL=100 pg/dL1\ \text{pg/mL} = 100\ \text{pg/dL}1 pg/mL=100 pg/dL
ng/L
1 ng/L=1 pg/mL1\ \text{ng/L} = 1\ \text{pg/mL}1 ng/L=1 pg/mL
pg%
\text{pg%} = \text{pg/dL}
Description
Placental Growth Factor (PlGF) is a proangiogenic protein produced primarily by:
- Trophoblasts (syncytiotrophoblasts)
- Placental endothelial cells
It plays a fundamental role in:
- Placental vascular development
- Uteroplacental blood flow
- Implantation
- Fetal growth
During normal pregnancy:
- PlGF rises sharply from 11–34 weeks,
- Peaks at ~28–30 weeks,
- Declines near term.
In preeclampsia, PlGF is markedly decreased.
Physiological Role
- Promotes angiogenesis
- Enhances vascular remodeling
- Supports placental perfusion
- Counterbalances anti-angiogenic proteins like sFlt-1 (soluble Fms-like tyrosine kinase 1)
PlGF is a central marker of placental function.
Clinical Significance
LOW PlGF (Most Important Finding)
Strongly associated with:
- Preeclampsia (early or late onset)
- Placental insufficiency
- Fetal growth restriction (FGR/ IUGR)
- Preterm birth due to placental disease
- Stillbirth risk
- Placental abruption
Low PlGF indicates anti-angiogenic imbalance, typically with high sFlt-1/PlGF ratio.
Cutoffs Used Clinically (FMF, FIGO, ACOG)
- PlGF < 100 pg/mL → high suspicion of preeclampsia
- PlGF < 12 pg/mL → highly specific for early-onset preeclampsia
- PlGF < 5th percentile for gestation → indicates placental dysfunction
- sFlt-1/PlGF ratio > 38 → predicts preeclampsia within 1 week
HIGH PlGF
Usually normal in healthy pregnancies.
Mildly elevated in:
- Multiple gestation (twins)
- Molar pregnancy
- High placental volume
- Normal late pregnancy (physiologic peak)
High PlGF is not clinically problematic.
Reference Intervals
PlGF Levels by Gestational Age
| Gestation | Reference Range (pg/mL) |
| 11–14 weeks | 20 – 150 |
| 15–19 weeks | 50 – 300 |
| 20–23 weeks | 100 – 600 |
| 24–28 weeks | 150 – 1000 |
| 29–33 weeks | 150 – 700 |
| 34–36 weeks | 100 – 400 |
| >37 weeks | 50 – 200 |
Important: Interpretation must use MoM (multiples of median) adjusted for gestational week.
Critical Values
- PlGF < 100 pg/mL at 20–34 weeks → strong predictor of preeclampsia
- PlGF < 12 pg/mL → very high risk of early severe PE
Diagnostic Uses
1. Preeclampsia Diagnosis (Major Use)
PlGF is used with:
- sFlt-1
- Uterine artery Doppler
- Mean arterial pressure
2. Rule-Out Test (Highly Valuable)
- Normal/high PlGF + low sFlt-1/PlGF ratio reliably rules out preeclampsia for 1–2 weeks.
3. Fetal Growth Restriction (FGR/IUGR)
Low PlGF correlates with:
- Placental insufficiency
- Abnormal Dopplers
- Preterm delivery risk
4. First Trimester Screening
Part of FMF preeclampsia predictive algorithm.
5. High-Risk Pregnancy Monitoring
Used in:
- Chronic hypertension
- Diabetes
- CKD
- Autoimmune disease
- Previous PE/FGR history
Analytical Notes
- Serum or EDTA plasma acceptable
- Homogeneous immunoassays and automated platforms available
- Hemolysis can falsely raise or lower PlGF depending on method
- Levels highly gestation-dependent - always reference gestational MoM
- Process sample promptly; freeze if delayed
Clinical Pearls
- Low PlGF is a strong early marker of placental dysfunction before clinical symptoms.
- sFlt-1/PlGF ratio is often more informative than PlGF alone.
- Normal PlGF essentially rules out preeclampsia for the next week (very high negative predictive value).
- PlGF levels are naturally lower in late pregnancy, so interpretation must be gestation-specific.
- Multiple gestation → higher baseline PlGF.
Interesting Fact
PlGF is part of the VEGF family, yet unlike VEGF-A, it acts almost exclusively on the placenta, making it an exceptionally specific biomarker for pregnancy-related vascular disorders.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Placental Biomarkers
- FIGO & ISUOG Preeclampsia Guidelines
- Fetal Medicine Foundation (FMF) - PlGF Algorithms
- ACOG Practice Bulletin - Gestational Hypertension & Preeclampsia
- Mayo Clinic Laboratories - PlGF
- ARUP Consult - Maternal-Fetal Biomarkers
- NIH / MedlinePlus - Placental Growth Factor Test