When to refer a pregnant patient with proteinuria (presence of excess proteins in the urine)?

From the Guidelines

Pregnant women with proteinuria should be referred to a specialist when protein levels exceed 300 mg in a 24-hour urine collection or when the protein-to-creatinine ratio is greater than 0.3, especially if accompanied by hypertension or other concerning signs. The management of proteinuria in pregnancy is crucial to prevent complications such as preeclampsia, which can lead to severe maternal and fetal outcomes 1. According to the ISSHP classification, diagnosis, and management recommendations, women with preeclampsia should be assessed in hospital when first diagnosed, and those with proteinuria and severe hypertension, or hypertension with neurological signs or symptoms, should receive MgSO4 for convulsion prophylaxis 1. Key points to consider when referring pregnant women with proteinuria include:

• Protein levels exceeding 300 mg in a 24-hour urine collection or a protein-to-creatinine ratio greater than 0.3
• Presence of hypertension (blood pressure ≥140/90 mmHg)
• New-onset proteinuria after 20 weeks gestation
• Proteinuria with symptoms like headache, visual disturbances, right upper quadrant pain, or edema
• Proteinuria with abnormal laboratory values (elevated liver enzymes, low platelets, or rising creatinine)
• Heavy proteinuria (>2 grams in 24 hours) even without hypertension The urgency of referral depends on gestational age and symptom severity, with third-trimester presentations requiring more immediate attention 1. Maternal monitoring in preeclampsia should include BP monitoring, repeated assessments for proteinuria if not already present, clinical assessment including clonus, and twice weekly blood tests for Hb, platelet count, liver transaminases, creatinine, and uric acid 1.

From the Research

Proteinuria in Pregnancy: When to Refer

• Proteinuria is a common test performed during pregnancy, with a classic cutoff of >300 mg/24 hours or a urine protein-to-creatinine ratio of at least 0.3 to define proteinuria 2
• The presence of proteinuria is sufficient but not necessary for the diagnosis of preeclampsia, and its management is almost identical to that of gestational hypertension without severe features 2
• The severity of blood pressures and presence of end-organ damage are more important factors influencing maternal and neonatal outcomes than the excess protein excretion 2

Referral Guidelines

• New-onset proteinuria before 20 weeks' gestation suggests known or previously undetected kidney disease, and warrants investigation and close surveillance 3
• Proteinuria detected after 20 weeks' gestation may indicate preeclampsia, and should be evaluated in the context of other clinical signs and symptoms 3, 4
• The amount of proteinuria does not seem to be related to poor maternal and neonatal outcomes, and monitoring proteinuria may lead to unindicated preterm deliveries and related neonatal complications 2, 5

Diagnostic Tests

• Spot urine protein-to-creatinine ratio is a reasonable "rule-out" test for proteinuria, with high sensitivity and specificity at a threshold of 30 mg/mmol 6
• Albumin-creatinine ratio may also be used to rule out significant proteinuria, although evidence is limited by paucity of data and wide confidence intervals around the result 6
• Urine dipstick screening for proteinuria does not provide any clinical benefit and should not be used to diagnose proteinuria 2