What are the laboratory findings in Nephrotic Syndrome?

From the Guidelines

Nephrotic syndrome is diagnosed based on the presence of proteinuria > 3.5 g/d AND serum albumin <30 g/l with or without edema, as defined by the KDIGO 2021 guideline for the management of glomerular diseases 1. To evaluate nephrotic syndrome, the following laboratory tests are essential:

• Urinalysis with microscopy
• Urine protein-to-creatinine ratio
• Serum albumin
• Lipid panel
• Comprehensive metabolic panel
• A 24-hour urine collection for protein quantification is crucial, with nephrotic-range proteinuria defined as >3.5g/24 hours in adults, as stated in the KDIGO 2021 guideline 1. Key characteristics of nephrotic syndrome include:
• Proteinuria > 3.5 g/d
• Serum albumin <30 g/l
• Presence of edema, especially in the presence of diffuse foot process effacement It is also important to evaluate for an underlying cause and exclude secondary forms of FSGS, as recommended by the KDIGO 2021 guideline 1. Additional tests may include:
• Complete blood count
• Serum electrolytes
• Coagulation studies due to increased thrombotic risk
• Serologic testing for potential causes, such as antinuclear antibodies, anti-double-stranded DNA, complement levels (C3, C4), hepatitis B and C serologies, HIV testing, and serum and urine protein electrophoresis.

From the Research

Nephrotic Syndrome Labs

Nephrotic syndrome is characterized by a triad of clinical features: oedema, substantial proteinuria (> 3.5 g/24 hours) and hypoalbuminaemia (< 30 g/L) 2. The diagnosis of nephrotic syndrome can be confirmed by measuring proteinuria and serum albumin and lipid levels.

• Proteinuria should be documented by a quantitative measurement e.g. urine protein: creatinine ratio (PCR) or albumin: creatinine ratio (ACR) 2.
• PCR > 300-350 mg/mmol indicates nephrotic range proteinuria 2.
• A urine total protein level of 3.5 g/d is equivalent to a urine albumin level of 2.2 g/d 3.
• Threshold levels for nephrotic-range proteinuria and albuminuria were close to the points of maximal accuracy for both outcomes 3.

Lab Tests for Nephrotic Syndrome

Lab tests for nephrotic syndrome include:

• Urine protein: creatinine ratio (PCR) 2
• Albumin: creatinine ratio (ACR) 2
• Serum albumin level 2, 4, 5, 6, 3
• Serum lipid level 2, 4, 5, 6
• Urine total protein level 3
• Urine albumin level 3

Diagnostic Criteria

The diagnostic criteria for nephrotic syndrome include:

• Urine total protein excretion greater than 3.5 g/d or total protein-creatinine ratio greater than 3.5 g/g 3
• Low serum albumin level (< 30 g/L) 2
• High serum cholesterol level 2, 4, 5, 6, 3
• Peripheral edema 2, 4, 5, 6, 3