Transthyretin, Pre Albumin

Immunology

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Description

Prealbumin, also known as transthyretin or thyroxine-binding prealbumin (TBPA), is a low molecular weight glycoprotein which transports about one third of the serum thyroxine and also retinol. Prealbumin is found complexed to retinol binding protein. Protein-calorie malnutrition can occur from poor dietary intake or from loss of nutrients due to disease for example in cancer, shock, infection, and surgical complications. Total parenteral nutrition carries with it risks of metabolic derangements associated with mode of feeding. Thus there may be times when assessment and monitoring of protein-calorie malnutrition is required. Prealbumin has a half life in plasma of around 2 days and is a more sensitive indicator of protein-energy status than albumin which has a much longer half-life [1]. Prealbumin is a better indicator of dietary intake rather than overall nutritional status [1]. The role of one off measurements of prealbumin are limited in screening for malnutrition [1]. Two measurements 3-5 days apart to assess the trend in prealbumin and CRP are probably more useful [1]. In ill patients, prealbumin levels are inversely related to CRP because in infection/inflammation there is a reprioritisation of synthesis towards acute phase proteins such as CRP [1]. Therefore an increase in prealbumin could be due to an improvement in metabolic status or an increased nutritional intake [1]. A low prealbumin can be used to identify patients who may require nutritional support. All hopitals should have protocols for assessing nutritional status and monitoring and these protocols may include serial measurements of CRP and prealbumin [1]. Prealbumin levels can be difficult to assess in patients with infection, inflammation or recent trauma because of the influence of transcapillary escape [1].

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Indications

Assessment of dietary intake/nutritional status.

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Sample Type

2mL Serum (Gel 5mL Yellow tube). Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

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Reference Range

Male 0.2 - 0.5 g/L.
Female 0.1 - 0.4 g/L.

Reference range established in house and PRU collaboration.

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Turnaround Time

Within 10 days

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Testing Frequency

Weekly

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References

Myron Johnson A, et al. Clinical indications for plasma protein assays: transthyretin (prealbumin) in inflammation and malnutrition. Clinical Chemistry & Laboratory Medicine. 2007. 45(3): 419-426.Skenkin A. Serum prealbumin: Is it a marker of nutritional status or of risk of malnutrition. Clin Chem. 2006. 52:2177-2179. [Ref 1]Devoto G, et al. Prealbumin serum concentrations as a useful tool in the assessment of malnutrition in hospitalized patients. Clinical Chemistry. 2006. 52(12): 2281-2285.Kuszajewski ML, Clontz AS. Prealbumin is best for nutritional monitoring. Nursing. 2005. 35(5):70-71.

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See Also

Serum Retinol Binding Protein

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