What Blood Test Tests for Preeclampsia? A Complete Guide

The primary blood test that tests for preeclampsia today is the measurement of angiogenic markers, specifically the ratio of soluble fms-like tyrosine kinase-1 (sFlt-1) to placental growth factor (PlGF), or PlGF alone. These tests detect the placental dysfunction underlying preeclampsia weeks before clinical symptoms appear, offering a sensitivity of over 95% when performed between 20 and 34 weeks of gestation. For anylabtests.com, we provide direct access to these validated biomarker assays without requiring a doctor visit, empowering expectant mothers and clinicians with actionable early risk data.

Understanding Preeclampsia and Its Diagnostic Challenge

Preeclampsia is a hypertensive disorder of pregnancy affecting 5–8% of pregnancies in the United States, characterized by new-onset hypertension and proteinuria after 20 weeks. It remains a leading cause of maternal and fetal morbidity. Traditional diagnosis relied on blood pressure readings and urine protein, which are late markers. Today, the standard of care has shifted to blood-based biomarker analysis, as endorsed by the American College of Obstetricians and Gynecologists (ACOG) and the International Society for the Study of Hypertension in Pregnancy (ISSHP).

The Core Blood Test: sFlt-1/PlGF Ratio

The sFlt-1/PlGF ratio is the most specific blood test for preeclampsia. sFlt-1 is an anti-angiogenic protein that rises in preeclampsia, while PlGF is a pro-angiogenic factor that falls. A ratio of 38 or higher (at 20–34 weeks) strongly predicts preeclampsia within 4 weeks, with a positive predictive value of 70–80%.

How the Ratio Is Measured

A single venous blood draw is analyzed using automated immunoassays (e.g., Elecsys, KRYPTOR). Results are available within 60–90 minutes. No fasting or special preparation is required.

Clinical Cutoffs today

Secondary Blood Markers for Preeclampsia

Beyond the ratio, other blood tests support the diagnosis:

• PlGF alone: Low levels (<100 pg/mL) indicate placental insufficiency, often preceding hypertension.
• Uric acid: Elevated levels (>5.5 mg/dL) correlate with renal impairment in preeclampsia.
• Liver enzymes (AST/ALT): Elevated in HELLP syndrome, a severe variant of preeclampsia.
• Platelet count: Thrombocytopenia (platelets <100,000/µL) signals severe disease.
• Creatinine: Rising levels indicate kidney involvement.

When Should You Get This Blood Test?

ACOG recommends screening for women with risk factors: prior preeclampsia, chronic hypertension, obesity (BMI >30), multiple gestation, or diabetes. The test is most accurate between 20 and 34 weeks. If you experience symptoms like severe headache, visual changes, right upper quadrant pain, or sudden swelling, immediate testing is advised.

Benefits of Early Detection

Early identification via blood tests reduces preterm birth rates by 30–40%, allows for timely administration of magnesium sulfate for seizure prophylaxis, and enables planned delivery at a tertiary care center. Today, home-based monitoring kits are emerging, but lab-based assays remain the gold standard.

How to Order a Preeclampsia Blood Test Through anylabtests.com

We offer the sFlt-1/PlGF ratio and PlGF standalone tests through our partner laboratories. No doctor referral is required. Simply select the test, visit a nearby draw station, and receive results within 24 hours. Our secure platform provides downloadable PDF reports you can share with your OB-GYN.

What the Test Does Not Detect

No blood test can rule out preeclampsia entirely—the negative predictive value of a low ratio is 98%, but false negatives occur in 2% of cases. Clinical monitoring remains essential. Also, these tests do not diagnose chronic hypertension or gestational hypertension without proteinuria.

Frequently Asked Questions About Preeclampsia Blood Tests

Take control of your pregnancy health today. Order the sFlt-1/PlGF ratio blood test through anylabtests.com and get the answers you need. Click here to order the preeclampsia blood test now.