HPE Human albumin handbook | Page 6

TABLE 1

Biological and functional properties of albumin and corresponding medical applications ( based on Rozga et al ¹ )

Functional / biological feature

Maintenance of oncotic pressure

Medical application

Second-line therapy of haemorrhagic shock , in case of inadequate response to first-line crystalloid fluids or non-protein colloids Treatment of ascites and peripheral oedema following liver transplantation

Inhibition of apoptosis

Haemostatic effects

Vascular integrity

Anti-inflammatory properties

Potentially sepsis

Extracorporeal circulation

Binding to leukotoxin in sepsis and shock Extensive burns during the period of transcapillary leakage

Decompensated liver cirrhosis

albumin < 35g / l , although clinically significant hypoalbuminaemia is probably identified by levels < 25g / l . Low serum albumin levels are risk factors and a predictor of morbidity / mortality regardless of the implicated disease . ¹² Intravenous administration of human albumin to treat hypoalbuminaemia is a controversial issue ; this is consistent with the principle that hypoalbuminaemia is often a “ symptom ” rather than a primary process . Overall , the purpose of albumin administration is not the correction of the oncotic pressure per se , but the correction of hypovolaemia and fluid depletion . Indeed , human albumin is used mainly in acute conditions , for the correction of fluid loss and restoration of blood volume , and in a few , selected

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chronic situations with low levels of serum albumin . Albumin is also used when the administration of nonprotein colloids is contraindicated . ¹⁴

However , its use in critically ill patients with volume or oncotic deficit is not unanimously supported by the evidence . Several studies have not uncovered a benefit for albumin in fluid resuscitation . Moreover , a meta-analysis of studies involving patients receiving intensive care for acute kidney injury showed that albumin was associated with worse outcomes in terms of mortality when compared with crystalloids such as normal saline , but these data were not subsequently confirmed in randomised clinical trials . ¹⁵ Despite the absence of robust comparative data , albumin is still used in cases requiring acute volume resuscitation owing to its non-oncotic properties and is beneficial for patients with extensive burns . In conditions involving systemic inflammation ( for example , acute lung injury or respiratory distress syndrome ), albumin improves oxygenation and haemodynamic status . Other medical applications include liver support therapy , including largepore haemofiltration and albumin exchange and dialysis , for liver failure and other types of toxicities , which consists in replacement of defective forms of albumin and albumin bound to bloodborne toxins with normal physiological protein . These therapeutic strategies can provide support to patients while they await liver transplantation or recovery from injury . ¹

Despite its beneficial effects in different scenarios , intravenous administration of albumin may cause side effects such as circulatory failure or local allergic reactions , asthma , hypotension , nausea and vomiting , and oedema . ² Nonetheless , its pleiotropic effects and non-oncotic properties such as immunodulation , antioxidation , and antiinflammatory activity provide the basis for its longterm use in patients with decompensated cirrhosis . Its effects were evaluated in this context in the ANSWER randomised clinical trial , where prolonged administration resulted in improved overall survival accompanied by a decreased rate of complications , and better quality of life for patients . However , these benefits were not confirmed in the MACHT study , which evaluated patients with cirrhosis awaiting liver transplantation . ¹⁶

Owing to its persistence in circulation and negligible immunological effect , albumin has been used as a stabiliser of other therapeutic proteins such as interferon , interleukin , and antibodies , and potentially can assume relevant roles in the targeted delivery of drugs . In cancer therapy , for example , albumin-bound chemotherapy agents are used in the treatment of metastatic breast cancer and have been tested for other types of malignancies . In addition , glycated albumin has the potential to function as an alternative biomarker for glycaemic control in patients with diabetes . ²

Conclusions Human albumin is the main determinant of plasma oncotic pressure and plays a pivotal role in modulating the distribution of fluids between compartments . Several clinical and experimental studies support the assumption that part of its therapeutic activity is also dependent on its nononcotic properties . As an important biological product used in clinical treatment , albumin has several indications supported by solid scientific evidence and shows potential in the improvement of drug delivery .

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