Albumin is a parameter on our in-house biochemistry panels. For me, it wasn't one I thought about tons before I got into medicine nursing. I'd look at the usuals, BUN/creatinine, ALT/ALP, etc, but the others I didn't really know that much about.

What does albumin actually do, though?

Well, albumin is a pretty important one! It is a plasma protein and is mainly responsible for maintaining colloidal oncotic pressure (COP) in the vascular space. It is this pressure that keeps fluid within the vessels – without the oncotic pull that albumin provides, fluid would leak through the vessel walls, causing oedema and third-spacing of fluids (fluid leakage into cavities).

Albumin loss can be seen secondary to medical disorders such as protein-losing nephropathy or protein-losing enteropathy, due to leakage through burns or haemorrhage through trauma, and in patients with inflammatory conditions.

In addition to the concerns regarding fluid balance and oncotic pull, albumin is required for the transport and metabolism of many protein-bound drugs, and drug overdoses may be seen in these patients, despite being given an appropriate dose, as there is more ‘free’ drug not bound to protein, which can affect the body.

What can we do about it?

Colloidal oncotic pressure can be increased by the administration of colloids with a higher molecular weight than albumin. Synthetic colloid agents have been the subject of investigation in veterinary medicine, after reports that they could be linked to acute kidney injury in human medicine, but are still used in some facilities; examples include gelatin-based products (e.g. Gelofusin) and hydroxyethyl starches (HES) such as hetastarch. Plasma is a natural colloid; however, it contains very little albumin and so very large volumes are required to increase albumin levels, risking volume overload. If your patient is eating, or will tolerate a feeding tube, the best way to increase their albumin naturally is with food!

References

1. Monitoring and Intervention for the Critical Ill Small Animal: The Rule of 20. Kirby & Linklater, 2017.