What labs are recommended for the diagnosis and management of preeclampsia?

Recommended Laboratory Tests for Diagnosis and Management of Preeclampsia

The diagnosis and management of preeclampsia require comprehensive laboratory testing including complete blood count, liver and renal function tests, and urine protein assessment at minimum twice weekly, with more frequent monitoring based on clinical changes. 1

Diagnostic Laboratory Tests

Initial Diagnosis

• Blood Pressure Measurement: Confirm hypertension (≥140/90 mmHg) using validated devices for pregnancy 1
• Proteinuria Assessment:
  • Automated dipstick urinalysis (screening)
  • If positive, quantify with urine protein/creatinine ratio (PCR)
  • PCR ≥30 mg/mmol (0.3 mg/mg) confirms abnormal proteinuria 1

Required Laboratory Tests

1. Complete Blood Count:

   • Hemoglobin and platelet count 1, 2
   • Low platelets (<100,000/mm³) indicate severe features 2

2. Liver Function Tests:

   • Aspartate aminotransferase (AST)
   • Alanine aminotransferase (ALT)
   • Lactate dehydrogenase (LDH)
   • Serum bilirubin
   • Serum albumin 1, 2

3. Renal Function Tests:

   • Serum creatinine
   • Blood urea nitrogen (BUN)
   • Serum electrolytes
   • Serum uric acid (associated with worse maternal and fetal outcomes) 1, 2

4. Coagulation Studies:

   • Indicated if platelets <100,000/mm³ 2
   • Activated partial thromboplastin time (aPTT) 3

Monitoring Protocol

Frequency of Testing

• Minimum: Twice weekly blood tests for all women with preeclampsia 1
• Additional testing: Perform immediately in response to clinical changes 1

Parameters to Monitor

• Blood Pressure: Regular monitoring, target diastolic BP of 85 mmHg and systolic BP <160 mmHg 1, 2
• Proteinuria: Repeated assessments if not already present 1
• Clinical Assessment: Including clonus and neurological symptoms 1

Indications for Delivery

Monitor for the following parameters that would necessitate delivery:

• Progressive thrombocytopenia
• Progressively abnormal renal or liver enzyme tests
• Pulmonary edema
• Abnormal neurological features (severe headache, visual scotomata)
• Non-reassuring fetal status 1

Special Considerations

Risk Factors for Adverse Outcomes

• Elevated red blood cell count
• Reduced platelet count
• Earlier gestational age at delivery 4

Postpartum Monitoring

• Continue monitoring BP at least every 4 hours for at least 3 days postpartum 1
• Repeat laboratory tests (Hb, platelets, creatinine, liver enzymes) the day after delivery and then every second day until stable 1
• Review at 3 months postpartum to ensure resolution of all abnormalities 2

Common Pitfalls to Avoid

1. Do not rely on proteinuria magnitude to determine disease severity or management decisions 5
2. Do not wait for complete symptom development before initiating treatment; early diagnosis and management are critical 5
3. Do not use serum uric acid levels alone as an indication for delivery, despite its association with worse outcomes 1
4. Avoid NSAIDs for postpartum analgesia in women with preeclampsia, especially with acute kidney injury 1, 2
5. Do not attempt to distinguish mild versus severe preeclampsia clinically as all cases may rapidly become emergencies 1

By following these laboratory testing protocols and monitoring parameters closely, clinicians can effectively diagnose preeclampsia, track disease progression, and make timely decisions regarding management and delivery to optimize maternal and fetal outcomes.