What is the normal serum prealbumin range and how should abnormal prealbumin levels be interpreted clinically?

Prealbumin: Normal Range and Clinical Interpretation

Direct Answer

The normal serum prealbumin range is ≥30 mg/dL, and values below this threshold warrant evaluation for protein-energy malnutrition, but prealbumin should never be interpreted in isolation without considering inflammatory status, renal function, and hepatic function. 1, 2

Normal Reference Range

• Target threshold: ≥30 mg/dL is the recommended outcome goal for prealbumin when monitoring nutritional status 1, 2
• Some research suggests 135 mg/L (13.5 mg/dL) or greater reflects return to stable nutritional status in patients receiving nutritional support 3
• Normal population mean is approximately 29.6 ± 4.82 mg/dL 4

Critical Limitations That Override Nutritional Interpretation

Inflammation (Most Important Confounder)

Prealbumin is a negative acute-phase reactant that declines during inflammation, infection, or critical illness regardless of actual nutritional intake. 1, 5, 2

• Inflammatory cytokines directly downregulate hepatic synthesis even when protein and caloric intake are adequate 5
• An elevated C-reactive protein negates the relationship between prealbumin and actual protein intake 5, 6
• The American College of Cardiology recommends that prealbumin should not be used as a primary marker of nutritional status in critically ill adults with suspected malnutrition 5

Renal Dysfunction (Artificial Elevation)

Prealbumin levels are artificially elevated in renal failure due to impaired kidney degradation, making interpretation unreliable in patients with impaired kidney function. 1, 5, 2

• This elevation occurs because the kidney normally degrades prealbumin, and when renal function is impaired, clearance is reduced 1
• Despite this limitation, values <30 mg/dL in dialysis patients are still associated with increased mortality risk 1

Hepatic Dysfunction

• Prealbumin is synthesized by the liver and is significantly decreased when liver function is impaired 7
• In acute viral hepatitis, prealbumin drops to approximately 15.3 ± 7.4 mg/dL, and in chronic liver diseases (cirrhosis, chronic active hepatitis), it drops to approximately 10 mg/dL 4
• Prealbumin may be more sensitive than albumin for detecting acute liver dysfunction 4

Clinical Interpretation Algorithm

Step 1: Check for Confounders FIRST

Before interpreting prealbumin as a nutritional marker, you must:

• Measure C-reactive protein alongside prealbumin to assess inflammatory status 5, 6
• Assess renal function (if impaired, prealbumin is unreliable for nutrition assessment) 1, 5
• Assess hepatic function (if impaired, low prealbumin reflects liver dysfunction, not just malnutrition) 7, 4

Step 2: Interpret Based on Clinical Context

If inflammation is present (elevated CRP):

• Low prealbumin reflects inflammation, not necessarily malnutrition 5, 6
• Do not use prealbumin to guide nutritional intervention decisions 5
• Use alternative assessment tools instead (see below) 5

If renal failure is present:

• Prealbumin values are artificially elevated and unreliable 1, 5
• However, in dialysis patients, values <30 mg/dL still predict increased mortality risk 1

If no inflammation and normal renal/hepatic function:

• Prealbumin <30 mg/dL warrants evaluation for protein-energy malnutrition 1, 2
• Prealbumin can complement clinical assessment but should not be used alone 8

Step 3: Use Superior Assessment Tools

The American Society for Parenteral and Enteral Nutrition recommends using Nutritional Risk Screening 2002 (NRS-2002), which incorporates BMI, weight loss, food intake, and disease severity. 5

• Subjective Global Assessment (SGA) is more reliable than albumin or prealbumin in detecting protein-energy wasting 5
• Body composition assessment should be preferred to biochemical markers when diagnosing and monitoring malnutrition 5
• Monitor food intake daily using semi-quantitative methods in malnourished patients 5
• Trigger nutritional intervention when intake is ≤50% of energy requirements over 3 days 5

Comparison to Albumin

There is insufficient evidence to conclude that prealbumin is a more sensitive or accurate index of malnutrition than serum albumin. 1, 2

• Prealbumin has a shorter half-life (2-3 days) compared to albumin (20 days), theoretically making it more responsive to acute changes 1, 5, 2
• However, prealbumin does not consistently correlate with changes in other nutritional parameters 1, 5
• Both are negative acute-phase reactants limited by the same confounding factors 1

Prognostic Value

Low prealbumin levels are strongly associated with increased mortality risk, particularly in dialysis patients. 1, 2

• Prealbumin levels at initiation of dialysis or during maintenance dialysis predict future mortality risk 1, 2
• Values <30 mg/dL correlate with other indices of protein-energy malnutrition 1

Common Pitfalls to Avoid

• Never interpret low prealbumin as malnutrition without ruling out inflammation first 5, 6
• Never use prealbumin to assess nutritional status in renal failure patients 1, 5, 2
• Never assume hypoprealbuminemia is solely due to malnutrition when inflammation may be the primary driver 5
• Never wait for laboratory confirmation to begin nutritional support if clinical signs of malnutrition are present 6
• Never interpret prealbumin in isolation without considering inflammatory status, renal function, and hepatic function 5, 6

Monitoring Nutritional Intervention

• Prealbumin changes more rapidly and accurately reflect current nutritional status compared to albumin when monitoring response to nutritional support 3
• In patients receiving enteral or parenteral nutrition with adequate caloric/protein goals, prealbumin concentration changes can guide effectiveness of intervention 3
• However, this utility is only valid in the absence of inflammation and normal renal/hepatic function 5, 9