What is the expected serum albumin range in patients with nephrotic syndrome?

From the Guidelines

**In patients with nephrotic syndrome, the expected serum albumin range is typically below 3.0 g/dL, often falling between 1.0-2.5 g/dL, as defined by the presence of proteinuria > 3.5 g/d and serum albumin <30 g/l with or without edema, especially in the presence of diffuse foot process effacement 1.** This hypoalbuminemia is a defining characteristic of the condition, alongside heavy proteinuria (>3.5 g/day), edema, and hyperlipidemia. The low albumin occurs because the damaged glomerular filtration barrier allows albumin to leak from the bloodstream into the urine at a rate that exceeds the liver's ability to synthesize new albumin. Some studies suggest using a serum albumin of ≤2.5 g/dL as a component of the definition of nephrotic syndrome for children, but the most recent guideline suggests a definition of <3 g/dL 1. However, based on the most recent and highest quality study, the serum albumin level should be considered below 3.0 g/dL in the context of nephrotic syndrome. Key characteristics of nephrotic syndrome include:

• Heavy proteinuria (>3.5 g/day)
• Hypoalbuminemia (serum albumin <30 g/l)
• Edema
• Hyperlipidemia Clinicians should monitor albumin levels regularly in nephrotic patients, as persistent severe hypoalbuminemia (<2.0 g/dL) may indicate poor response to therapy and increased risk for complications such as thromboembolism and infections. Treatment focuses on addressing the underlying cause of nephrotic syndrome while providing supportive care to manage symptoms and complications associated with hypoalbuminemia.

From the Research

Serum Albumin Range in Nephrotic Syndrome

• The expected serum albumin range in patients with nephrotic syndrome is typically low, with a level often considered as less than 3.5 g/dL 2.
• Nephrotic syndrome is characterized by hypoproteinemia, which includes low serum albumin concentrations, often accompanied by edema formation and other signs and symptoms 3.
• Studies have shown that patients with nephrotic syndrome may have serum albumin levels that are significantly lower than normal, with some studies indicating a range of less than 3.5 g/dL as a common threshold for diagnosis 2, 4.
• The low serum albumin level in nephrotic syndrome is due to the increased urinary excretion of albumin and other serum proteins, which can lead to hypoproteinemia and edema formation 3.
• Some studies have reported specific serum albumin levels in patients with nephrotic syndrome, such as a level of less than 3.5 g/dL in patients with diabetic kidney disease 2, and lower levels of albumin in patients with primary systemic amyloidosis and nephrotic syndrome 5.

Factors Affecting Serum Albumin Levels

• Dietary protein intake can affect serum albumin levels in patients with nephrotic syndrome, with high protein intake potentially leading to increased albumin synthesis, but also increased glomerular permeability and albumin loss in the urine 3.
• The use of certain medications, such as angiotensin-converting enzyme inhibitors, may help to reduce albuminuria and increase serum albumin levels in patients with nephrotic syndrome 3.
• The severity of kidney disease and the presence of other complications, such as hypertension and hyperlipidemia, can also impact serum albumin levels in patients with nephrotic syndrome 4.

Clinical Implications

• The diagnosis and management of nephrotic syndrome often involve monitoring serum albumin levels, as well as other clinical parameters, such as urine protein excretion and kidney function 2, 4.
• The prognosis and outcome of patients with nephrotic syndrome can be influenced by various factors, including the underlying cause of the syndrome, the severity of kidney disease, and the presence of other complications 4.