Do critically ill patients in the intensive care unit typically have low serum albumin?

Do Critically Ill Patients Have Low Albumin?

Yes, hypoalbuminemia is extremely common in critically ill patients in the intensive care unit, occurring primarily due to systemic inflammation that directly suppresses hepatic albumin synthesis, not malnutrition. 1, 2

Prevalence and Mechanisms

Critically ill patients routinely develop low serum albumin through several well-defined pathophysiological mechanisms:

Primary Mechanism: Inflammatory Suppression

• Inflammatory cytokines directly downregulate hepatic albumin synthesis, even when protein and caloric intake are adequate. 1, 2 This is the dominant mechanism in the ICU setting.
• Albumin functions as a negative acute-phase reactant; C-reactive protein and other positive acute-phase proteins are inversely correlated with serum albumin levels. 2
• The postoperative period typically shows a 10-15 g/L decrease in albumin due to inflammatory cytokines and transcapillary loss. 1, 2

Additional Contributing Factors

• Extravascular protein redistribution and increased peripheral catabolism are major factors responsible for hypoalbuminemia in critically ill patients, even when albumin synthesis rates are supranormal. 3
• Transcapillary albumin loss occurs during acute illness and critical care states. 1
• Hemodilution from fluid resuscitation decreases measured serum albumin concentration. 2

Clinical Significance

Prognostic Value

Each 10 g/L (1.0 g/dL) decline in serum albumin significantly raises the odds of mortality by 137% and morbidity by 89% in critically ill patients. 4 This powerful association reflects disease severity and inflammatory burden rather than nutritional status. 2, 4

Typical Thresholds in Critical Illness

• Serum albumin <35 g/L is associated with increased morbidity and mortality risk. 2
• Mean serum albumin levels in seriously ill injured and septic ICU patients average approximately 20 g/L (range: 12.5-26.9 g/L). 3

Critical Distinction: Inflammation vs. Malnutrition

The most important clinical pitfall is assuming hypoalbuminemia in critically ill patients reflects malnutrition when inflammation is the predominant driver. 2, 4

• The American Society for Parenteral and Enteral Nutrition explicitly states that serum albumin is primarily an indicator of inflammation, not malnutrition. 2
• Inflammation causes the same changes in serum protein levels as protein-energy malnutrition, even with adequate caloric and protein intake. 2
• The association between hypoalbuminemia and poor outcomes appears independent of both nutritional status and inflammation. 4

Management Implications

When NOT to Give Albumin

In critically ill adult patients (excluding thermal injuries and ARDS), intravenous albumin is not suggested for first-line volume replacement or to increase serum albumin levels. 1 This is a conditional recommendation with moderate certainty of evidence. 1

• Balanced crystalloids are the preferred first-line resuscitation fluid in general ICU populations. 1
• Targeting a specific albumin level (e.g., 30 g/L) with daily albumin infusions in critically ill patients may be associated with significantly higher rates of pulmonary edema and fluid overload without improving outcomes. 1

Specific Exceptions in Cirrhosis

Albumin administration has defined roles in critically ill patients with cirrhosis for select indications:

• Large-volume paracentesis (>5L): 8 g albumin per liter removed. 1
• Spontaneous bacterial peritonitis: 1.5 g/kg on day 1.0 g/kg on day 3. 1
• Hepatorenal syndrome-AKI: 1 g/kg on day 1, then 20-40 g daily with vasopressors. 1

Practical Assessment Algorithm

When encountering hypoalbuminemia in a critically ill patient:

1. Measure C-reactive protein immediately to quantify the inflammatory burden. 2
2. Assess volume status clinically (edema, ascites, pleural effusions) to identify hemodilution. 2
3. Evaluate for external protein losses (proteinuria, dialysate losses if applicable). 2
4. Treat the underlying inflammatory condition rather than the albumin level itself. 2, 5
5. Do NOT routinely administer albumin to "correct" the number unless specific cirrhosis-related indications exist. 1