Some practical points

A large number of endogenous and exogenous toxins, including drug-overdoses, can be removed from the body by albumin-facilitated extracorporeal dialysis, which also passively can remove water-soluble, non-binding toxins. The most effective and widely used system for this purpose seems to be the Molecular Adsorbent Recirculating System (MARS). For a review, see Mitzner, S.R. (2011). Extracorporeal liver support-albumin dialysis with the Molecular Adsorbent Recirculating System (MARS). Ann. Hepatol. 10 Suppl. 1, S21-28. Also other albumin-based extracorporeal detoxifiers exist, for example Single-Pass Albumin Dialysis (SPAD). For a discussion of these and other types of extracorporeal clearance procedures, see the chapter “Albumin dialysis” written by Taguchi, K., Chuang, V.T.G. & Otagiri, Otagiri, M., Chuang, V.T.G., Maruyama, T. & Kragh-Hansen, U. (editors). (2013). Human serum albumin. New insights on its structural dynamics, functional impacts and pharmaceutical applications. Sojo University Publishing Center, Kumamoto, Japan. pp. 401-415.

Albumin-bound ligands can be removed from the protein by using, for example, charcoal, resins or dextrans. In addition, microporous hollow-fibre membranes which can adsorb endotoxin from solutions of albumin have been constructed by Bell, C.M., Guo, K. & Wendel, H.P. [(2007). Endotoxin removal from albumin and saline solutions. Int. J. Artif. Organs 30, 589-593].

Urinary albumin has been quantified by using size-exclusion HPLC. However, due to the presence of coeluting globulins this approach systematically gives higher values than, for example, immunoassays (Sviridov, D., Meilinger, B., Drake, S.K., Hoehn, G.T. & Hortin, G.L. (2006). Coelution of other proteins with albumin during size-exclusion HPLC: Implications for analysis of urinary albumin. Clin. Chem. 52, 389-397). Quantification of urinary albumin can also be influenced by fragments and modified forms of the protein (Hortin, G.L. & Sviridov, D. (2008). Analysis of molecular forms of albumin in urine. Proteomics Clin. Appl. 2, 950-955).

Quality control of albumin depletion for proteomic studies has been examined by Seam, N., Gonzales, D.A., Kern, S.J., Hortin, G.L., Hoehn, G.T. & Suffredini, A.F. [(2007). Quality control of serum albumin depletion for proteomic analysis. Clin. Chem. 53, 1915-1920].

The use of proteomics for efficient, accurate and complete analysis of clinical samples poses a variety of technical challenges. For example, the presence of higher abundance proteins in plasma, such as albumin, may mask the detection of lower abundance proteins such as the cytokines. However, solving this problem by depletion of albumin from plasma also results in a non-specific loss of cytokines and other proteins (Granger, J., Siddiqui, J., Copeland, S. & Remick, D. (2005). Albumin depletion of human plasma also removes low abundance proteins including the cytokines. Proteomics 5, 4713-4718).

A high-throughput, solution-based method for drug library screening with albumin has been developed by Flarakos, J., Morand, K.L. & Vouros, P. [(2005). High-throughput solution-based medicinal library screening against human serum albumin. Anal. Chem. 77, 1345-1353].

The progress and history of dye-binding methods for albumin assay have been reviewed by Doumas, B.T. & Peters, T. Jr. [(2009). Origins of dye-binding methods for measuring serum albumin. Clin. Chem. 55, 583-584 and (1997). Serum and urine albumin: a progress report on their measurement and clinical significance. Clin. Chim. Acta 258, 3-20].

REVISED 24.11.2017