Prealbumin

Order Code

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4909

Preferred Specimen

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Collect 1 mL of serum. Allow the serum separator tube (SST) to clot in an upright position for a minimum of 30 minutes. Centrifuge the specimen within 2 hours of collection. Store refrigerated.

ContainerType

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Serum separator tube

Alternate Specimen Requirements

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If using a plain red-top tube, collect 1 mL of serum. Let the sample clot upright for at least 60 minutes. Centrifuge and transfer the serum to a plastic transport tube within 2 hours. Clearly label the tube as “serum from red-top tube.” Keep refrigerated.

Mnimum Volume

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0.25 mL

Transport Temperature

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Refrigerated

Expected Turnaround Time

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1-2 days

Specimen Stability

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3 days room temperature; 3 days refrigerated; 6 months frozen

Methodology

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Roche COBAS immunoturbidimetric Note: STAT or regional laboratory testing may use different methodology and/or manufacturer

Rejection Criteria

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• Gross hemolysis

Overview

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Prealbumin, also referred to as transthyretin, is a transport protein produced predominantly by the liver. Its name reflects its migration position ahead of albumin on serum protein electrophoresis (SPEP). It plays a key role in transporting thyroid hormones (thyroxine and triiodothyronine) and the retinol-binding protein–vitamin A complex.

Due to its relatively short half-life (~48 hours), prealbumin levels drop quickly—typically within 3 to 4 days—following inadequate protein or caloric intake. Levels normalize promptly upon nutritional repletion. In addition to malnutrition, low concentrations of prealbumin can occur in inflammatory states, malignancy, and hepatic or renal dysfunction, reflecting its function as a negative acute phase reactant.

Clinical Significance

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• Primarily used to assess recent nutritional intake, particularly in individuals with known medical conditions (e.g., cancer, malabsorption syndromes)
• Evaluation of unexplained weight loss or failure to thrive
• Assessment of protein loss in conditions such as nephrotic syndrome or protein-losing enteropathies
• Particularly beneficial for monitoring nutrition in hospitalized patients due to its short half-life
• Useful for gauging the effectiveness of nutritional interventions or supplementation

Additional Information

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Compared to other serum proteins used in nutritional assessment—such as albumin, transferrin, fibronectin, or retinol-binding protein—prealbumin is often preferred due to its intermediate half-life and more immediate response to nutritional changes (Bernstein, 1989; Chwals, 1992; Winkler, 1989).

Interpretative Information

Decreased Prealbumin Levels May Indicate:

• Protein-energy malnutrition
• Acute or chronic illness (sepsis, trauma)
• Systemic inflammation
• Liver disease (e.g., cirrhosis)
• Certain cancers
• Nephrotic syndrome
• Protein-losing enteropathies
• Hyperthyroidism
• Major burns (>30% of body surface area)
• Zinc deficiency

Elevated Prealbumin Levels May Be Associated With:

• Tumors producing transthyretin
• High-dose corticosteroid therapy
• Hyperactive adrenal function
• Acute alcohol intoxication
• Use of certain NSAIDs at high doses
• Hodgkin lymphoma
• Renal failure

Limitations

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A single measurement may not be sufficient for reliable assessment of nutritional status. Sequential testing, typically 3–5 days apart, is recommended to monitor trends (Shenkin, 2006).

Prealbumin may not be a reliable nutritional marker in the presence of inflammation or infection, as it functions as a negative acute phase reactant.

Certain medications may interfere with prealbumin levels:

• Decreased levels: amiodarone, estrogen therapy
• Increased levels: prednisolone, androgens, anabolic steroids

References

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Diagnostic Role

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Prealbumin is a good clinical marker of nutritional status (protein intake and synthesis) due to its high ration of essential to non essential amino acids. Its short half-life of approximately 48 hours allows for changes in nutrition levels to be seen quickly. The ability to test for prealbumin is widely available and inexpensive.

Hospitalized patients who are malnourished are more likely to develop clinical complications and have poorer outcomes, as well as increased length of stay. (Shenkin, 2006) A low prealbumin level helps identify patients with a poor nutritional status who would benefit from nutritional assessment and supplementation. In high-risk hospitalized patients, prealbumin levels should be checked twice weekly. A low or decreasing level promptly indicates declining nutritional status, indicating the need of more aggressive intervention. In the presence of adequate protein-calorie support, prealbumin levels return to normal within 8 days. (Beck, 2002)

One significant limitation of prealbumin, however, is its down-regulation when systemic inflammation is present, often characterized by reprioritization of synthesis toward acute-phase reactants, such as C-reactive protein (CRP). This may be seen in serious illness where low serum prealbumin is common and inversely related to CRP. When other nutritional assessment indicates adequate protein-calorie supplementation, serial measurements of prealbumin and CRP concentrations help identify concomitant inflammation which may be attributing to a false-low prealbumin. (Davis, 2011)

Alias

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• Transthyretin

Test Setup Days

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Monday through Friday PM shift

CPT

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84134 LOINC: 14338-8

Reference Range

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20-40 MG/DL