In a pregnant patient with urine creatinine 145 mg/dL, urine protein 73 mg/dL, resulting in a protein‑to‑creatinine ratio of 0.50, does this represent clinically significant proteinuria and fulfill laboratory criteria for pre‑eclampsia, and what are the appropriate next steps in management?

Urine Protein-to-Creatinine Ratio of 0.50 mg/mg Exceeds the Diagnostic Threshold for Preeclampsia

Your patient's protein-to-creatinine ratio of 0.50 mg/mg (500 mg/g) exceeds the diagnostic threshold of ≥0.3 mg/mg (≥300 mg/g or ≥30 mg/mmol) for clinically significant proteinuria in pregnancy and fulfills laboratory criteria for preeclampsia when combined with new-onset hypertension after 20 weeks gestation. 1

Diagnostic Confirmation

• The International Society for the Study of Hypertension in Pregnancy (ISSHP) establishes that a 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. 1

• Your patient's ratio of 0.50 mg/mg is 67% above the diagnostic threshold, placing her clearly in the range of clinically significant proteinuria. 1

• Research evidence demonstrates strong correlation between spot UPCR and 24-hour protein excretion in suspected preeclampsia (r=0.828), with a cutoff of 0.28 mg/mg showing 60.4% sensitivity and 77.9% specificity for 300 mg/24h proteinuria. 2 Your patient's value of 0.50 mg/mg far exceeds this threshold.

Critical Clinical Context Required

Preeclampsia diagnosis requires BOTH proteinuria AND new-onset hypertension (≥140/90 mmHg) after 20 weeks gestation. 3

• Measure blood pressure immediately; if ≥140/90 mmHg, the diagnosis of preeclampsia is confirmed. 3

• If blood pressure is normal (<140/90 mmHg), this represents isolated proteinuria and does not meet criteria for preeclampsia, despite the elevated protein-to-creatinine ratio. 3

• Proteinuria ≥3.5 g/24h (UPCR ≥3.5 mg/mg) without concurrent hypertension does not constitute preeclampsia. 3

Severity Stratification

• Your patient's UPCR of 0.50 mg/mg represents moderate proteinuria (approximately 500 mg/24h), not nephrotic-range proteinuria (>3.5 g/24h). 1, 3

• Massive proteinuria (>5 g/24h or UPCR >5 mg/mg) is associated with more severe neonatal outcomes and earlier delivery, but your patient's level does not reach this threshold. 1

• A UPCR >900 mg/mmol (approximately >8 mg/mg if age >35 years) correlates with worse maternal outcomes; your patient's value is well below this high-risk threshold. 1

Immediate Management Algorithm

If Blood Pressure ≥140/90 mmHg (Preeclampsia Confirmed):

Step 1: Determine Gestational Age 3

• If ≥37 weeks: Proceed directly to delivery after maternal stabilization. 3

• If <37 weeks: Assess for severe features requiring expedited delivery within 24-48 hours. 3

Step 2: Blood Pressure Management 3

• If BP 140-159/90-109 mmHg: Initiate oral methyldopa, labetalol, or nifedipine targeting diastolic 85 mmHg and systolic 110-140 mmHg. 3

• If BP ≥160/110 mmHg: Urgent treatment with oral nifedipine or IV labetalol/hydralazine in a monitored setting, with confirmation within 15 minutes. 3

Step 3: Seizure Prophylaxis 3

• Consider magnesium sulfate, particularly if additional risk factors are present (uric acid >5.9 mg/dL, P/C ratio >4.9, or symptoms). 3

Step 4: Fetal Assessment 3

• Perform ultrasound evaluation of fetal growth, as proteinuria is linked to placental insufficiency. 3

• Initiate non-stress testing to monitor fetal well-being. 3

Step 5: Maternal Monitoring 1

• Twice-weekly blood tests for hemoglobin, platelets, liver and renal function. 1

• Assess for warning symptoms requiring immediate action: new-onset headache, epigastric or upper-quadrant pain with vomiting, or visual disturbances—all mandate urgent evaluation and often accelerated delivery. 3

If Blood Pressure <140/90 mmHg (Isolated Proteinuria):

• This does not represent preeclampsia; investigate alternative causes of proteinuria (underlying renal disease, urinary tract infection). 3

• Refer to nephrology for evaluation of primary renal disease. 3

• Monitor blood pressure closely, as preeclampsia may develop later in pregnancy. 1

Important Caveats

• Do not repeat proteinuria measurements to guide timing of delivery; proteinuria fluctuates and does not predict outcomes, so management should focus on blood pressure control, gestational age, and maternal/fetal clinical status. 3

• 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). 1

• A 24-hour urine collection is not necessary for diagnosis or management decisions; the spot UPCR provides sufficient information. 1 Reserve 24-hour collections only for confirming nephrotic-range proteinuria (>3.5 g/day) when making thromboprophylaxis decisions. 3

Postpartum Follow-Up

• Close monitoring for 48-72 hours postpartum is necessary, as 20% of HELLP cases occur within 48 hours of delivery. 3

• Reassess proteinuria at 3 months postpartum; if persistent, it indicates underlying primary renal disease requiring nephrology referral. 3