Urgent considerations
See Differentials for more details
Although proteinuria is rarely a medical emergency, the presence of certain clinical features may indicate a more serious disease process warranting immediate assessment. New-onset proteinuria with features of systemic disease (e.g., progressive renal dysfunction, other organ system abnormalities) should be assessed as soon as possible.
Renal vein thrombosis
Patients with nephrotic-range proteinuria and marked hypoalbuminaemia (generally <20 g/L [<2.0 g/dL]) who present with acute renal failure or concern for pulmonary embolism may have renal vein thrombosis. The diagnosis is further suggested by new-onset haematuria, acute flank pain, and increasing proteinuria. Diagnosis can be confirmed by renal ultrasonography, magnetic resonance venography, and traditional venography. Anticoagulation is the mainstay of therapy, with catheter-directed thrombolysis being used in select circumstances.[45] These patients are also at risk of lower-extremity deep venous thrombosis.
Rapidly progressive glomerulonephritis
Consider rapidly progressive glomerulonephritis in patients with proteinuria, haematuria, and acute renal failure. Diagnostic efforts to assess for aetiologies of acute renal failure (e.g., post-infectious glomerulonephritis, systemic lupus erythematosus, membranoproliferative glomerulonephritis, IgA nephropathy, thrombotic microangiopathy, anti-glomerular basement membrane disease, anti-neutrophil cytoplasmic antibody [ANCA]-associated vasculitis) should be made immediately. This may include appropriate serological testing and renal biopsy. Failure to diagnose a rapidly progressive glomerulonephritis may lead to irrecoverable loss of kidney function, morbidity, and even death.
Pre-eclampsia
New-onset proteinuria may be a sign of pre-eclampsia in pregnant women. Finding 1+ of protein on a urine dipstick should prompt an enquiry about symptoms of pre-eclampsia (visual disturbance, headache, epigastric pain, and oedema), measurement of blood pressure, and quantification of proteinuria.[31] These women should be referred urgently to an obstetrician to assess fetal wellbeing and to consider urgent delivery. Untreated pre-eclampsia may progress to eclampsia, a life-threatening condition characterised by grand mal seizures in a woman with pre-eclampsia.[46]
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