How is prealbumin related to albumin?

Aside from being synthesized in the liver and serving as a transport protein in the blood, prealbumin (PA) doesn’t really have much in common with albumin. More specifically, PA is not derived from albumin and, in fact, the two proteins are structurally distinct from each other!

So where does PA get its name? PA is the original name for transthyretin (TTR), a transport protein that primarily carries thyroxine (T4) and a protein bound to retinol (vitamin A). The name arose because TTR migrated faster than albumin on gel electrophoresis of human serum.1

Because of its much shorter serum half-life compared to that of albumin ( ~2 days vs ~20 days),2 PA is more sensitive to recent changes in protein synthesis and more accurately reflects recent dietary intake (not necessarily overall nutritional status) than albumin. 3

But, just like albumin, PA may represent a negative acute phase reactant, as its synthesis drops during inflammatory states in favor of acute phase reactants such as C-reactive protein. 4 So be cautious about interpreting low PA levels in patients with active infection, inflammation or trauma.

 

Reference

  1. Socolow EL, Woeber KA, Purdy RH, et al. Preparation of I-131-labeled human serum prealbumin and its metabolism in normal and sick patients. J. Clin Invest 1965; 44: 1600-1609. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC292644/
  2. Oppenheimer JH, Surks MI, Bernstein G, and Smith JC. Metabolism of Iodine-131-labeled Thyroxine-Binding Prealbumin in Man. Science 1965; 149: 748-750. https://www.ncbi.nlm.nih.gov/pubmed/14330531
  3. Ingenbleek Y, Young VR. Significance of prealbumin in protein metabolism. Clin Chem Lab Med 2002; 40: 1281-1291. https://www.ncbi.nlm.nih.gov/pubmed/12553432
  4. Shenkin A. Serum prealbumin: is it a marker of nutritional status or of risk of malnutrition? Clin Chem 2006;52:2177 – 2179. http://clinchem.aaccjnls.org/content/52/12/2177

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Contributed by Colin Fadzen, Medical Student, Harvard Medical School, Boston, MA.

 

 

How is prealbumin related to albumin?

My elderly patient with acute heart failure with preserved ejection fraction (HFpEF) has a low serum albumin. Can hypoalbuminemia be associated with HFpEF?

Absolutely! As early as 1959, Guyton and Lindsey demonstrated the importance of serum colloid osmotic pressure in the pathogenesis of pulmonary edema1.

Specifically, they found that in dogs with normal plasma protein concentrations fluid began to transudate into the lungs when the left atrial pressure rose above an average of 24 mm Hg vs only 11 mm Hg when plasma protein concentration was reduced by about 50%.

Fast forward to 2003, Arques et al studied serum albumin and pulmonary artery wedge pressures in 4 groups of patients: acute HFpEF, heart failure with reduced ejection fraction (HFrEF), acute dyspnea from pulmonary origin and normal controls2.   Patients with HFpEF were significantly more likely to have hypoalbuminemia , compared to those with HFrEF, pulmonary disease or normal controls.  The main cause of hypoalbuminemia in the HFpEF was malnutrition in 77% and/or sepsis in 41% of patients.   Hypoalbuminemia was inversely related to age and plasma C-reactive protein.

Perhaps, we should pay more attention the nutritional status of our patients with HFpEF!

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References

  1. Guyton AC, Lindsey AW. Effect of elevated left atrial pressure and decreased plasma protein concentration on the development of pulmonary edema. Circ Res 1959;7: 649-657.
  2. Arquès S, Ambrosi P, Gélisse R et al. Hypoalbuminemia in elderly patients with acute diastolic heart failure. J Am Coll Card 2003;42:712-16. http://www.onlinejacc.org/content/42/4/71                                                                                                    
My elderly patient with acute heart failure with preserved ejection fraction (HFpEF) has a low serum albumin. Can hypoalbuminemia be associated with HFpEF?