From the Guidelines
Laboratory tests to assess for preeclampsia include a full blood count, liver enzymes, serum creatinine, electrolytes, uric acid, urinalysis, and microscopy, as well as PCR or albumin: creatinine ratio, as recommended by the ISSHP 1. These tests are essential for diagnosing and determining the severity of preeclampsia, which can rapidly progress to eclampsia or HELLP syndrome, requiring prompt intervention to prevent maternal and fetal complications. Key laboratory tests include:
- A full blood count to evaluate for thrombocytopenia
- Liver enzymes, such as aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, to assess liver function
- Serum creatinine, electrolytes, and uric acid to evaluate kidney function
- Urinalysis and microscopy, as well as PCR or albumin: creatinine ratio, to assess for proteinuria Additionally, a renal ultrasound may be recommended if serum creatinine or any of the urine testing are abnormal 1. It is crucial to note that the ISSHP recommends that all women with chronic hypertension in pregnancy have these tests performed at first diagnosis to provide a baseline reference should suspicion arise later in pregnancy of superimposed preeclampsia 1. Recent guidelines also emphasize the importance of automated blood pressure measurement, dipstick proteinuria testing, and quantitative testing by urinary protein-to-creatinine ratio or 24-hour urine collection 1. However, the most recent and highest-quality study, published in 2022, highlights the importance of a comprehensive approach to diagnosing and managing preeclampsia, including the use of laboratory tests and clinical evaluation 1.
From the Research
Laboratory Tests for Preeclampsia
The following laboratory tests are used to assess for preeclampsia:
- Liver enzyme testing 2
- Placental growth factor (PlGF) and soluble FMS like tyrosine kinase 1 (sFlt-1) assays 2
- Hematocrits, prothrombin time, partial thromboplastin time, aspartate aminotransferase, alanine aminotransferase, and bilirubins 3
- Platelets counting 3
- Lactic dehydrogenase 3
- Uric acid 3
- Seric creatinine 3, 4
- Serum creatinine and liver function tests 4
- Spot urinary protein to creatinine ratio (PCR) 5
Diagnostic Criteria
The American College of Obstetricians and Gynecologists criteria are used as the gold standard for diagnosing preeclampsia 3, 4
- Systolic blood pressure is as important as diastolic blood pressure in the diagnosis of preeclampsia 4
- Changes in proteinuria are not predictive of disease severity or maternal or fetal complications 4
- Symptoms of cerebral involvement, such as headache and visual changes, or signs of end-organ involvement, including abnormal laboratory tests, are evidence of preeclampsia with severe features 4
Laboratory Test Sensitivity and Specificity
The sensitivity and specificity of various laboratory tests for preeclampsia are: