What laboratory tests are indicated for nephrotic syndrome and nephritic syndrome?

From the Guidelines

For nephrotic and nephritic syndrome evaluation, essential labs include urinalysis with microscopy, urine protein-to-creatinine ratio, serum creatinine, blood urea nitrogen, complete blood count, serum albumin, and lipid panel, as recommended by the most recent guidelines 1.

Key Laboratory Tests

• Urinalysis with microscopy to assess for hematuria, proteinuria, and casts
• Urine protein-to-creatinine ratio to quantify proteinuria
• Serum creatinine and blood urea nitrogen to evaluate renal function
• Complete blood count to assess for anemia, leukocytosis, or thrombocytosis
• Serum albumin and lipid panel to evaluate for hypoalbuminemia and hyperlipidemia

Nephrotic Syndrome Evaluation

• 24-hour urine protein collection to confirm proteinuria >3.5g/day
• Additional tests to identify underlying causes, such as hepatitis B and C serology, HIV testing, and serum and urine protein electrophoresis

Nephritic Syndrome Evaluation

• Complement levels (C3, C4) and serologic tests like anti-nuclear antibody, anti-neutrophil cytoplasmic antibody, anti-glomerular basement membrane antibody, and anti-streptolysin O titers
• Renal ultrasound to assess kidney size and structure
• Renal biopsy remains the gold standard for definitive diagnosis, especially in adults with unexplained proteinuria or hematuria, as stated in the 2021 KDIGO guideline 1.

Importance of Recent Guidelines

The 2021 KDIGO guideline for the management of glomerular diseases provides the most recent and highest quality evidence for the evaluation and management of nephrotic and nephritic syndrome, and should be followed in clinical practice 1.

From the Research

Labs to Get for Nephrotic and Nephritic Syndrome

To diagnose and manage nephrotic and nephritic syndrome, several laboratory tests are essential. These tests help establish the presence of proteinuria, hematuria, and other abnormalities associated with these conditions.

• Urine Tests:
  • Urine protein: creatinine ratio (PCR) or albumin: creatinine ratio (ACR) to document proteinuria 2
  • Dipstick test to detect hematuria
• Blood Tests:
  • Serum albumin levels to diagnose hypoalbuminemia 2, 3
  • Lipid profile to assess hyperlipidemia 2, 3
  • Renal function tests, including eGFR, to evaluate kidney function 4, 3
  • Blood pressure monitoring to detect hypertension 5, 4
• Imaging and Biopsy:
  • Renal biopsy to establish the underlying cause of nephrotic or nephritic syndrome and guide management 2, 6, 3
  • Imaging studies may be used to assess kidney structure and function, although they are not always necessary for diagnosis
• Other Tests:
  • Tests to rule out secondary causes of nephrotic syndrome, such as diabetes mellitus, systemic lupus erythematosus, and amyloidosis 2, 3
  • Tests to assess for complications, including venous thrombosis and infection 3