Proteinuria Assessment in Preeclampsia

Primary Recommendation

• The International Society for the Study of Hypertension in Pregnancy (ISSHP) recommends using Urine Protein-to-Creatinine Ratio (UPCR) for preeclampsia assessment, as there is currently insufficient data to recommend using urinary albumin/creatinine ratio (UACR) 1, 2, 3.
• UPCR is the endorsed standard for quantifying proteinuria in suspected preeclampsia, according to the ISSHP 1, 4, 5.

Practical Assessment Algorithm

Initial Screening

• Automated dipstick urinalysis is recommended as the initial screening test for proteinuria, with a threshold of ≥1+ proteinuria (≥30 mg/dL) to proceed to quantification with spot UPCR, as suggested by the ISSHP 1, 3.
• If dipstick shows ≥1+ proteinuria (≥30 mg/dL), proceed to quantification with spot UPCR, according to the ISSHP guidelines 1, 3.

Diagnostic Threshold

• UPCR ≥30 mg/mmol (or ≥0.3 mg/mg) indicates significant proteinuria and confirms the diagnosis when combined with new-onset hypertension after 20 weeks gestation, as recommended by the ISSHP 1, 4, 5, 3.

Clinical Significance of Proteinuria Quantification

Prognostic Value

• Massive proteinuria (>5 g/24h) is associated with more severe neonatal outcomes and earlier delivery, according to the ISSHP 1, 3.
• UPCR >900 mg/mmol (or >500 mg/mmol if age >35 years) correlates with worse maternal outcomes, as suggested by the ISSHP 1, 2.

Important Caveats

Proteinuria is Not Required for Diagnosis

• Preeclampsia can be diagnosed without proteinuria if new-onset hypertension after 20 weeks is accompanied by other end-organ dysfunction (thrombocytopenia, renal insufficiency, liver dysfunction, pulmonary edema, or neurological symptoms), as stated by the ISSHP 1, 3.

False Results

• Dipstick testing may miss some proteinuric cases, but when missed, total protein excretion is usually <400 mg/day, according to the ISSHP 1, 2, 3.
• UPCR <30 mg/mmol occasionally gives false-negative results for abnormal 24-hour proteinuria, though again typically when total excretion is minimal, as noted by the ISSHP 1, 2, 3.

Monitoring Considerations

• If proteinuria is initially diagnosed but subsequent dipsticks become negative, repeat quantification with UPCR to confirm whether true proteinuria persists, as recommended by the ISSHP 1, 2.
• Maternal monitoring should include repeated assessments for proteinuria if not already present, along with twice-weekly blood tests for hemoglobin, platelets, liver and renal function, according to the ISSHP 4, 5.