Nephrotic Syndrome Diagnosis

Core Diagnostic Criteria

The American Academy of Pediatrics and other medical societies recommend that proteinuria ≥3.5 g/24 hours is the threshold for nephrotic-range proteinuria in adults 1, 2
Serum albumin <3.0 g/dL defines hypoalbuminemia in adults, according to the National Kidney Foundation 1, 2
Edema is typically present as a clinical manifestation of nephrotic syndrome, as noted by the American College of Physicians 1
In children, proteinuria ≥40 mg/h/m² or first morning UPCR of ≥2 g/g is considered nephrotic-range proteinuria, as recommended by the Pediatric Nephrology Society 1, 2
Serum albumin ≤2.5 g/dL is the lower threshold for hypoalbuminemia in children, according to the American Academy of Pediatrics 1, 2

The National Kidney Foundation recommends quantifying proteinuria with 24-hour urine collection or spot urine protein:creatinine ratio (PCR) or albumin:creatinine ratio (ACR) 2
A complete blood count with platelets is recommended as part of the initial diagnostic evaluation, as noted by the American College of Physicians 1
The American Society of Nephrology recommends a comprehensive metabolic panel, including serum albumin, electrolytes, creatinine, urea, and glucose, as part of the initial diagnostic evaluation 2

The American Academy of Pediatrics recommends that children under 12 years old should not undergo kidney biopsy at initial presentation, unless atypical features are present 1, 2
The National Kidney Foundation recommends that kidney biopsy is indicated only for steroid resistance in children under 12 years old 1
In children 12 years and older and adults, kidney biopsy is recommended to determine the underlying cause before initiating immunosuppressive therapy, as recommended by the American Society of Nephrology 1, 2

The American College of Chest Physicians recommends assessing venous thromboembolism (VTE) risk, particularly when serum albumin falls below 2.9 g/dL 1, 2
Membranous nephropathy carries a higher VTE risk than other causes of nephrotic syndrome, as noted by the National Kidney Foundation 1

The European Society of Pediatric Nephrology recommends performing infectious screening for congenital syphilis and congenital CMV in cases of congenital nephrotic syndrome (age <3 months) 3, 4
Genetic testing is essential in cases of congenital nephrotic syndrome, as most cases are caused by genetic abnormalities, according to the International Society of Nephrology 3, 5, 4