What is the typical serum uric acid level in pregnancy‑induced hypertension (PIH)?

Serum Uric Acid Levels in Pregnancy-Induced Hypertension

Serum uric acid levels are elevated in pregnancy-induced hypertension (PIH), typically ranging from 5.5-6.5 mg/dL or higher, compared to normal pregnancy values of approximately 4.0-4.5 mg/dL. 1

Diagnostic Testing Recommendations

Major guidelines recommend measuring serum uric acid as part of the initial workup for hypertension in pregnancy:

• The International Society for the Study of Hypertension in Pregnancy (ISSHP) recommends serum uric acid testing at first diagnosis of chronic hypertension in pregnancy to establish a baseline reference for detecting superimposed preeclampsia 1
• The International Society of Hypertension guidelines include serum uric acid (s-UA) as part of the investigation panel for hypertension in pregnancy 1
• Testing should be performed alongside full blood count, liver enzymes, serum creatinine, electrolytes, and urinalysis 1

Typical Uric Acid Values by Condition

The following ranges have been documented in research studies:

• Normal pregnancy: 4.0-4.7 mg/dL 2, 3, 4
• Mild PIH/gestational hypertension: 5.4-5.6 mg/dL 2, 3, 4
• Severe PIH/preeclampsia: 6.2-6.7 mg/dL 2, 3, 4
• PIH with HELLP syndrome: 6.8-7.4 mg/dL (382-412 μmol/L) 5

Clinical Significance and Interpretation

A serum uric acid level ≥5.5 mg/dL is considered an indicator of PIH and correlates with disease severity:

• Levels ≥5.5 mg/dL show 79% sensitivity and 71% specificity for diagnosing PIH 2
• In women with chronic hypertension, uric acid ≥5.5 mg/dL increases the likelihood of superimposed preeclampsia (likelihood ratio 2.5) 4
• Elevated gestation-corrected uric acid levels are associated with worse maternal and fetal outcomes and should prompt detailed assessment of fetal growth 1

Important Clinical Caveats

While uric acid is elevated in PIH, guidelines emphasize specific limitations:

• Serum uric acid is NOT a diagnostic criterion for preeclampsia and should not be used alone to determine timing of delivery 1
• The test shows better diagnostic efficiency than creatinine for PIH (79% vs 63% sensitivity) but has limited utility in differentiating between various hypertensive disorders of pregnancy 2, 4
• Uric acid levels do not reliably predict the severity of HELLP syndrome once it develops 5
• The correlation between uric acid and clinical outcomes is weak (r = 0.06 to 0.26), though the association with severity of hypertension and proteinuria is stronger 5, 4

Practical Application

Use serum uric acid as part of a comprehensive assessment panel:

• Obtain baseline uric acid at diagnosis of any hypertensive disorder in pregnancy 1
• Values ≥5.5 mg/dL warrant increased surveillance for progression to preeclampsia, particularly in women with gestational hypertension or chronic hypertension 3, 4
• Serial measurements can help monitor disease progression, though clinical decisions should be based on the complete clinical picture including blood pressure trends, proteinuria, symptoms, and laboratory markers 1
• Hyperuricemia (>5.5 mg/dL) is associated with increased perinatal morbidity and mortality 3