Diagnosing Nephrotic Syndrome

Core Diagnostic Criteria

The American College of Physicians recommends that adults require >3.5 g/24 hours of proteinuria, while children need ≥40 mg/h/m² or first morning UPCR of ≥2 g/g for a diagnosis of nephrotic syndrome 1
The National Kidney Foundation suggests that serum albumin <3.0 g/dL in adults and ≤2.5 g/dL in children is indicative of hypoalbuminemia in nephrotic syndrome 1
Hyperlipidemia is often present in nephrotic syndrome, although it is not required for diagnosis, according to the Praxis Medical Insights 1

The European Renal Association recommends a clinical assessment to evaluate for edema, hypertension, and signs of volume status in patients with suspected nephrotic syndrome 2
Urinalysis should quantify proteinuria with urine protein:creatinine ratio (PCR) or albumin:creatinine ratio (ACR), as suggested by the National Institute for Health and Care Excellence 1
Blood biochemistry tests, including complete blood count, serum albumin, electrolytes, creatinine, urea, lipid profile, and glucose, are recommended by the American Society of Nephrology 1, 2

The International Society of Nephrology states that minimal change disease is the most common cause of nephrotic syndrome in children under 12 years, and initial treatment with glucocorticoids without biopsy is standard 1
The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend that children over 12 years and adults undergo kidney biopsy to determine the underlying cause of nephrotic syndrome, except in cases with positive serum anti-phospholipase A2 receptor antibodies 1, 3

The American Academy of Pediatrics suggests that minimal change disease is the most common primary cause of nephrotic syndrome in children 3, 1

The National Kidney Foundation recommends evaluating the risk of thromboembolism in patients with nephrotic syndrome, particularly when serum albumin <2.9 g/dL, as stated in the Praxis Medical Insights 1

The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines note that the albumin assay method affects results, with 2.5 g/dL with bromocresol green equaling approximately 2.0 g/dL with bromocresol purple, as reported in the Kidney International journal 3, 1
The European Renal Association emphasizes the importance of kidney biopsy in guiding management, especially in adults and children with steroid resistance, as stated in the Kidney International journal 3, 1