Preeclampsia is a serious pregnancy complication that typically develops after 20 weeks of gestation, or even postpartum. It involves new onset high blood pressure and can affect various organ systems in the body, posing risks to both the pregnant individual and the baby. Early detection and consistent monitoring are important for managing this condition, and blood tests serve as a tool in this process.
The Role of Blood Tests
Blood tests provide objective data that helps healthcare providers in the management of preeclampsia. These tests are useful for initial screening, confirming a suspected diagnosis, and monitoring the condition’s progression. While clinical symptoms like elevated blood pressure are often the first indicators, blood tests offer a deeper look into how the body’s organs are functioning. They complement physical examinations by revealing internal changes that might not be immediately apparent, allowing for timely interventions.
Specific Blood Markers and Their Significance
A range of specific blood tests are performed to assess for preeclampsia, each measuring different markers that indicate organ function or potential complications.
A Complete Blood Count (CBC) is a common test that includes a platelet count. In preeclampsia, a low platelet count, known as thrombocytopenia, can occur, indicating issues with blood clotting. Platelet counts below 150,000/microL are observed in about 20% of preeclampsia patients.
Liver Function Tests (LFTs) measure enzymes like Aspartate Aminotransferase (AST) and Alanine Aminotransferase (ALT), which can become elevated if the liver is affected by preeclampsia. Elevated levels of AST and ALT, often defined as more than two times the upper limit of normal, suggest impaired liver function.
Kidney function is assessed through tests measuring Creatinine and Blood Urea Nitrogen (BUN) levels. In a typical pregnancy, creatinine levels usually decrease due to increased kidney filtration. However, in preeclampsia, elevated creatinine levels, generally above 1.1 mg/dL, indicate impaired kidney function. Similarly, elevated BUN levels, often above 16.2 mg/dL, can also point to kidney involvement.
Uric acid levels are frequently elevated in preeclampsia and can be one of the earlier laboratory findings. While uric acid is a waste product normally filtered by the kidneys, its levels may rise if kidney damage occurs. An elevated serum uric acid level, such as above 5.6 mg/dL, is a common observation.
Newer biomarkers like the soluble fms-like tyrosine kinase-1 (sFlt-1) to placental growth factor (PlGF) ratio provide more advanced insights into placental health. PlGF promotes the development of new blood vessels, while sFlt-1 acts to inhibit this process. An imbalance, specifically a high sFlt-1/PlGF ratio, indicates an anti-angiogenic state associated with preeclampsia and can help predict the condition’s progression to severe features or adverse outcomes. For instance, an sFlt-1/PlGF ratio above 38 suggests a high likelihood of preeclampsia.
Understanding Your Test Results
Interpreting blood test results for preeclampsia involves looking at the combination of findings across different markers rather than focusing on a single value. Normal ranges for these markers can vary, and what is considered “normal” in a non-pregnant individual may differ during pregnancy. Abnormal findings across multiple tests often point towards a preeclampsia diagnosis or worsening condition.
For instance, a low platelet count, combined with elevated liver enzymes (AST and ALT), and high creatinine levels, collectively suggest organ dysfunction consistent with preeclampsia. A protein-to-creatinine ratio greater than 0.3 in a urine sample, roughly equivalent to 300 mg or more of protein over 24 hours, also indicates kidney involvement. It is important to remember that the amount of protein in the urine does not determine the severity of preeclampsia. Healthcare professionals consider the full clinical picture, including blood pressure readings and symptoms, when interpreting these results to determine the appropriate course of action.
When and How Testing Occurs
Preeclampsia blood tests are performed at various stages during pregnancy and the postpartum period, depending on the clinical situation. During routine prenatal check-ups, healthcare providers typically monitor blood pressure and perform urine tests for protein, which can be an early sign of the condition. If new symptoms of preeclampsia arise, such as new onset high blood pressure, persistent headaches, or vision changes, additional blood tests are usually ordered.
For ongoing monitoring once preeclampsia is diagnosed, blood tests are repeated to track the condition’s progression and assess the health of the mother and baby. For instance, sFlt-1 and PlGF biomarker tests can be used in the second and third trimesters to assess the risk of preeclampsia progressing to severe features. The blood draw process itself is straightforward, involving a simple collection of a blood sample from a vein, typically in the arm. This sample is then sent to a laboratory for analysis.