What is the effect of albumin (human albumin) infusion on haemoglobin (Hb) levels?

Effect of Albumin on Hemoglobin Levels

Albumin administration causes a significant hemoglobin dilution of approximately 5 g/L on average, with hemodilution effects lasting for at least 12 hours after administration. 1

Mechanism and Extent of Dilution

Albumin causes hemodilution through several mechanisms:

1. Volume expansion effect:

   • 5% albumin expands plasma volume by approximately double the volume infused 2
   • 20% albumin (hyperoncotic) can expand plasma volume by 1.9-2.2 times the infused volume 3

2. Distribution pattern:

   • When 5% albumin is infused, both plasma volume and interstitial fluid volume expand by approximately equal amounts 2
   • With normal saline, the expansion ratio of plasma to interstitial fluid is about 1:3 2

3. Duration of effect:

   • Hemodilution from albumin persists for at least 12 hours after administration 1
   • Isooncotic albumin solution (5%, 25g in 500mL) may cause hemoglobin decreases greater than 8 g/L 1

Clinical Implications

Transfusion Considerations

• The significant hemodilution effect may cause hemoglobin levels to drop below transfusion thresholds, potentially increasing the need for RBC transfusions 1
• In surgical patients, 30 minutes after infusion of approximately 20 mL/kg of 5% albumin, only 38±21% of the volume remained in the intravascular space 4

Fluid Management

• Albumin is recommended for specific clinical scenarios such as:
  • Large-volume paracentesis (>5L) at a dose of 6-8g per liter of fluid removed 5
  • Spontaneous bacterial peritonitis (1.5g/kg on day 1, followed by 1g/kg on day 3) 6, 5
  • Hepatorenal syndrome in combination with vasoconstrictors 5

Monitoring Recommendations

• When administering albumin, especially in patients with borderline hemoglobin levels:
  • Monitor hemoglobin levels before and after administration
  • Be aware that the dilutional effect may be misinterpreted as blood loss
  • Consider the prolonged hemodilution effect when planning subsequent interventions

Factors Affecting Albumin Distribution

The extent of hemodilution varies based on:

1. Patient condition:

   • Patients with hypoproteinemia experience greater loss of albumin to extravascular compartments 7
   • In septic patients, fluid may move from intracellular to extracellular space after albumin infusion 2

2. Albumin concentration:

   • Hyperoncotic albumin (20%) has approximately 5 times stronger volume expansion effect than crystalloids 3
   • Isooncotic albumin (5%) causes more significant hemodilution than equivalent volumes of crystalloids 1

3. Infusion rate and volume:

   • Rapid infusion of large volumes causes more pronounced immediate hemodilution 4
   • After experimental blood loss, infused albumin disappears at a rate of 45-106 mL per hour 7

Practical Applications

• For paracentesis: When using albumin (6-8g/L of fluid removed) for large-volume paracentesis, expect hemoglobin dilution and monitor accordingly 6
• For critical care: In ICU patients receiving albumin, anticipate a hemoglobin drop of approximately 5 g/L and consider this when evaluating for potential bleeding 1
• For surgical patients: Be aware that only about 40% of infused albumin volume remains intravascular after 30 minutes 4

Understanding the hemoglobin-diluting effect of albumin is essential for proper interpretation of laboratory values and clinical decision-making regarding transfusion requirements.