How can I prepare a 5% albumin solution from a 20% albumin stock?

Preparing 5% Albumin from 20% Albumin Stock

To prepare 5% albumin from 20% albumin stock, dilute 1 part of 20% albumin with 3 parts of 0.9% normal saline (NaCl) to achieve a final 1:4 dilution ratio.

Dilution Formula and Calculation

• Use the formula C₁V₁ = C₂V₂, where 20% × V₁ = 5% × V₂, resulting in a 1:4 dilution (1 part albumin to 3 parts diluent) 1

• For example, to prepare 100 mL of 5% albumin: mix 25 mL of 20% albumin with 75 mL of 0.9% NaCl 1

• For 500 mL of 5% albumin: mix 125 mL of 20% albumin with 375 mL of 0.9% NaCl 1

Critical Safety Considerations: Choice of Diluent

Never use sterile water alone as the diluent—this creates a hypotonic solution that causes fatal hemolysis in recipients. 2

• Only use 0.9% normal saline (NaCl) as the primary diluent for albumin dilution to maintain isotonicity 2

• If sodium load is a clinical concern, 5% dextrose may be used as an alternative diluent, but sterile water alone is absolutely contraindicated 2

• Between 1994-1998, at least 10 episodes of hemolysis (including one fatality) occurred in the United States when 25% albumin was incorrectly diluted with sterile water alone 2

Clinical Context for Dilution

• Both 5% and 25% albumin solutions are isotonic when properly prepared, but the 5% solution delivers approximately five-fold more sodium than concentrated formulations 3

• In the United States, both 5% and 25% albumin solutions are commercially available; in Europe, only 20% solution is typically available, necessitating dilution for certain indications 3

• The dilution from 20% to 5% is most commonly needed when large-volume, lower-concentration albumin is preferred for general volume resuscitation rather than oncotic support 4

Practical Preparation Steps

1. Calculate the required volume of 20% albumin (final volume ÷ 4) 1
2. Draw the calculated volume of 20% albumin into a sterile container 2
3. Add three times that volume of 0.9% NaCl to achieve 1:4 dilution 2
4. Mix gently but thoroughly to ensure homogeneous distribution 2
5. Label clearly with final concentration (5%), preparation date, and expiration 2

Storage and Stability

• Freshly diluted albumin should be used immediately when possible 2

• If storage is necessary, diluted albumin standards can be aliquoted and frozen for later use without significantly affecting protein concentration accuracy 5

• The aluminum content of albumin products should not exceed 200 µg/L, and the sodium content of 25% albumin is approximately 145 mEq/L 4