What labs should be ordered for a 36‑week pregnant woman with severe hypertension (blood pressure 163/98 mm Hg) to assess for pre‑eclampsia and HELLP syndrome?

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Laboratory Workup for Pregnancy-Induced Hypertension at 36 Weeks

Order a complete blood count with platelet count, comprehensive metabolic panel including liver enzymes (AST, ALT, LDH), serum creatinine, uric acid, and quantitative proteinuria assessment (protein-to-creatinine or albumin-to-creatinine ratio) immediately. 1, 2

Essential Laboratory Panel

This blood pressure of 163/98 mmHg meets criteria for severe hypertension (≥160/110 mmHg systolic or ≥110 mmHg diastolic) and requires urgent evaluation for preeclampsia and HELLP syndrome. 1, 2

Core Labs to Order Immediately:

  • Complete blood count (CBC) with platelet count – essential for detecting thrombocytopenia (platelets <100,000/μL), which defines the "LP" in HELLP syndrome 1, 2

  • Liver function tests including AST, ALT, and LDH – elevated liver enzymes (AST/ALT >2× upper limit normal) define the "EL" in HELLP and often precede platelet decline 1, 3

  • Serum creatinine and electrolytes – renal insufficiency is a diagnostic criterion for preeclampsia and indicates organ dysfunction 1, 2

  • Serum uric acid – serves as a prognostic marker (not diagnostic) for disease severity and should be measured as part of baseline assessment 1, 4

  • Hematocrit and peripheral blood smear – to assess for hemolysis, the "H" in HELLP syndrome 1

  • Serum haptoglobin – the most sensitive early marker for hemolysis in HELLP syndrome 3

  • Quantitative proteinuria assessment – either spot urine protein-to-creatinine ratio or albumin-to-creatinine ratio (≥30 mg/mmol or 265 mg/g indicates significant proteinuria) 1

Critical Clinical Context

Why This Matters at 36 Weeks:

At 36 weeks gestation with severe-range blood pressure, you are evaluating for preeclampsia with severe features versus HELLP syndrome, both of which require prompt delivery once maternal stabilization is achieved. 1, 5

Important Diagnostic Nuances:

  • Proteinuria is NOT required for preeclampsia diagnosis – it is absent in approximately 25% of cases, and 5-15% of HELLP syndrome patients have minimal or no proteinuria 2, 3

  • Hypertension may be absent in up to 20% of HELLP syndrome cases, so normal blood pressure does not exclude the diagnosis if other features are present 3

  • AST/ALT elevation often precedes platelet decline in HELLP syndrome, making liver enzymes particularly important for early detection 3

Timing Considerations:

  • Severe hypertension (≥160/110 mmHg) requires confirmation within 15 minutes – do not delay laboratory workup while repeating blood pressure 1, 2

  • Do not wait for laboratory results to initiate antihypertensive therapy if blood pressure remains ≥160/110 mmHg – treatment should begin within 30-60 minutes 2

Additional Assessments

While awaiting laboratory results:

  • Assess for symptoms of severe features: persistent headache, visual changes (scotoma, photopsia, blurred vision), epigastric or right upper quadrant pain, nausea/vomiting 2, 3

  • Obtain fetal heart rate tracing to assess fetal well-being 2

  • Check for hyperreflexia with clonus – indicates central nervous system irritability 2

Common Pitfalls to Avoid

  • Do not dismiss the diagnosis if proteinuria is absent – preeclampsia can present without proteinuria when other organ dysfunction is present 2, 3

  • Do not delay treatment waiting for "complete" laboratory panels – severe hypertension alone warrants immediate antihypertensive therapy 2

  • Do not use uric acid level alone to determine delivery timing – it must be interpreted alongside other markers of disease severity 4

  • Do not overlook HELLP syndrome if blood pressure is only mildly elevated – 20% of HELLP cases lack severe hypertension 3

Immediate Management Implications

Based on laboratory results:

  • If HELLP syndrome is confirmed (hemolysis + elevated liver enzymes + platelets <100,000/μL), plan for prompt delivery once coagulopathy and severe hypertension are corrected 1

  • Initiate magnesium sulfate for seizure prophylaxis if severe hypertension or neurological symptoms are present 1, 2

  • Administer betamethasone for fetal lung maturity if delivery is anticipated (though at 36 weeks, this is less critical than at earlier gestational ages) 1

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

2
Guideline

Classification and Management of Hypertensive Disorders in Pregnancy

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

3
Research

HELLP syndrome.

Journal of perinatal medicine, 2000

4
Guideline

Prognostic Value of Serum Uric Acid in Preeclampsia

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

5
Research

Hypertensive Disorders of Pregnancy.

American family physician, 2024

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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