Updated July 2026 · 8 min read

Albumin: The ICU Nurse's Guide

Part of the ICU Pharmacology Hub — browse every related guide in one place.

Albumin is the colloid critical care keeps arguing about. It's a blood product that stays in the vessels longer than saline, has a handful of situations where the evidence genuinely supports it, and a lot of situations where it's used out of habit. Knowing which is which — and the difference between 5% and 25% — is what separates informed administration from expensive fluid.

What albumin does

Albumin is the main protein responsible for holding fluid inside blood vessels (oncotic pressure). Infused, it expands intravascular volume and holds it there longer than crystalloid, which distributes throughout the extracellular space. That's the theory behind colloids. In practice, the survival benefit over cheaper crystalloid is limited to specific scenarios, which is why albumin is targeted rather than routine.

5% vs. 25% — not interchangeable

The concentration determines the effect.

5% albumin is approximately iso-oncotic and is used as a volume expander — resuscitation in shock, replacement in paracentesis. It adds volume roughly equal to what you infuse.

25% albumin ("salt-poor") is concentrated and pulls interstitial fluid into the vessels, so a small volume recruits a larger intravascular volume. It's used where you want oncotic pull without a large sodium/volume load — hepatorenal syndrome, SBP, and select edematous states, often paired with diuretics.

Where the evidence supports it

In cirrhosis in particular, albumin has become a well-supported adjunct: after draining several liters of ascites, albumin replacement prevents the circulatory collapse that follows, and in SBP it improves outcomes alongside antibiotics.

Where it isn't the answer

Two habits deserve retiring. First, treating a low serum albumin lab value by infusing albumin — the low number usually reflects illness, inflammation, and dilution, and topping it up doesn't fix the underlying process or reliably help outcomes. Second, using albumin as nutrition — it isn't absorbed or used as a protein source in any meaningful nutritional way. It also should be avoided as routine resuscitation fluid in traumatic brain injury, where it performed worse than saline.

Administration and safety

It's a blood product. Albumin is derived from pooled human plasma and heat-treated; institutions have specific handling and documentation requirements, though it doesn't require type-and-cross or the same reaction monitoring as red cells.

Watch for volume overload. Because albumin expands and holds intravascular volume, it can precipitate pulmonary edema in patients with poor cardiac or renal reserve. Monitor respiratory status and check for rising work of breathing, especially with 25%.

Reactions. Allergic and febrile reactions are uncommon but possible; hypotension has been reported with rapid infusion. Follow the ordered rate.

Bottom line

Albumin earns its place in a defined set of situations — large-volume paracentesis, spontaneous bacterial peritonitis, hepatorenal syndrome, and select shock resuscitation — and mostly wastes money and risks overload everywhere else. Know your concentration (5% expands, 25% concentrates), match it to the indication, watch for pulmonary edema, and resist the reflex to chase a low albumin number or use it as nutrition. Used for the right physiology, it's a genuinely valuable tool; used out of habit, it's just costly saline.

This article is general educational information for licensed clinicians and students, not medical advice or a substitute for your institution's protocols, pharmacy guidance, or a provider's orders. Always follow facility policy and verify doses independently.