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Prealbumin (Transthyretin)

Prealbumin (transthyretin) is a hepatically synthesized visceral protein with a ~ 2-day half-life that transports thyroid hormones and vitamin A.[1][2] Like albumin, it is a negative acute-phase protein — and the ASPEN 2021 position paper is unambiguous that prealbumin reflects inflammation and nutrition risk rather than nutritional status.[3]

Key Cutoff​

  • < 15 mg/dL — abnormal.
  • Useful primarily for tracking response to nutritional support over days-to-weeks, not for initial diagnosis of malnutrition.

Why Prealbumin Was Historically Preferred Over Albumin​

Prealbumin emerged in the 1990s as a "more sensitive" nutritional marker on the strength of its shorter half-life — ~ 2 days vs ~ 20 days for albumin — under the assumption that this kinetic advantage would translate into a more rapid readout of protein-energy status.[3] A 1995 roundtable and a wave of subsequent publications promoted it as the preferred laboratory measurement for assessing nutrition and monitoring response to support.[3]

Why This Paradigm Has Been Overturned​

The same limitations that apply to albumin apply to prealbumin — its serum concentration is driven predominantly by inflammation, not by nutritional intake:

  • Negative acute-phase reactant — During inflammation, hepatic protein synthesis shifts away from prealbumin toward positive acute-phase reactants (CRP, fibrinogen). Prealbumin declines in proportion to inflammatory severity, regardless of nutritional status.[3]
  • Does not correlate with nutrient delivery — Davis et al. found that prealbumin changes correlated with CRP changes (inverse, statistically significant) but not with caloric or protein delivery in patients on enteral nutrition.[4][3]
  • Confounded by renal disease — Prealbumin is renally excreted, so levels may be falsely elevated in kidney disease, further limiting interpretive value.[5][6]
  • Does not decline with starvation alone — In healthy individuals, prealbumin does not fall until BMI drops below ~ 12 after ≥ 6 weeks of starvation.[7]

ASPEN Position (2021)​

  • Prealbumin is not a component of any accepted definition of malnutrition (GLIM, AND/ASPEN consensus).[3]
  • It should not serve as a proxy for total body protein or muscle mass.[3]
  • It should not guide therapeutic changes in nutrition support, as it has not been shown to be a sensitive marker of energy and protein-intake adequacy.[3]
  • Normalization of prealbumin may indicate resolution of inflammation and transition to anabolism rather than response to nutrition therapy.[3]

Where Prealbumin May Still Have Value​

Despite its limitations as a nutritional marker, prealbumin retains some clinical utility:

  • Prognostic indicator (ICU) — In critically ill patients, a decline in prealbumin over time is independently associated with in-hospital mortality (OR 0.94, 95% CI 0.90–0.98, P = .002), though baseline prealbumin alone is not associated with mortality or LOS.[8]
  • Monitoring inflammation resolution — When trended alongside CRP, prealbumin can help differentiate inflammatory-driven declines from nutritional deficiency. As CRP falls below ~ 2 mg/dL, a subsequent rise in prealbumin may signal return to anabolic metabolism.[6][9]
  • Non-inflamed patients — One nuanced analysis suggests prealbumin can diagnose malnutrition and its severity in patients without an inflammatory syndrome, with proposed cut-offs of 0.17 g/L for malnutrition and 0.12 g/L for severe malnutrition (prospectively validated). Utility is limited to the inflammation-free subset.[10][1]

Practical Approach​

The ACG guideline reinforces that neither albumin nor prealbumin should be used as a marker for adequacy of nutrition therapy — levels will only rise once inflammation and oxidative stress abate.[11] CRP alone or in combination with prealbumin may provide useful information regarding changes in inflammatory state. A practical institutional approach is to trend prealbumin alongside CRP throughout admission to differentiate inflammatory-driven declines from poor nutrition.[9]

Reconstructive Relevance​

  • More useful than albumin for monitoring — Prealbumin's short half-life makes it preferable for tracking week-to-week response to perioperative oral nutritional supplements (ONS), immunonutrition, or TPN over the elective-reconstruction optimization window. It is not preferable for initial diagnosis.
  • GLP-1 receptor agonist users — Patients on GLP-1 RAs at the time of surgery have lower preoperative prealbumin in addition to lower albumin — a mechanistic signal for the wound-healing risk emerging in the reconstructive literature (Lee 2025; Koenig 2026). Trend prealbumin alongside CRP if GLP-1 RA exposure is recent and elective reconstruction is planned.
  • Free-flap monitoring — In chronic-wound free-tissue-transfer cohorts, prealbumin trending with CRP has been used to time secondary procedures and to flag patients whose flap recipient-bed biology is being driven by inflammation rather than by nutritional repletion.[9]
  • Do not use prealbumin to decide whether to proceed with elective reconstruction. Use it to monitor an established optimization plan once malnutrition has been diagnosed by appropriate tools.

See Also​

References​

1. Dellière S, Cynober L. "Is Transthyretin a Good Marker of Nutritional Status?" Clinical Nutrition. 2017;36(2):364–370. doi:10.1016/j.clnu.2016.06.004

2. National Library of Medicine (MedlinePlus). "Prealbumin Blood Test." Accessed 2026.

3. Evans DC, Corkins MR, Malone A, et al. "The Use of Visceral Proteins as Nutrition Markers: An ASPEN Position Paper." Nutrition in Clinical Practice. 2021;36(1):22–28. doi:10.1002/ncp.10588

4. Davis CJ, Sowa D, Keim KS, Kinnare K, Peterson S. "The Use of Prealbumin and C-Reactive Protein for Monitoring Nutrition Support in Adult Patients Receiving Enteral Nutrition in an Urban Medical Center." JPEN. Journal of Parenteral and Enteral Nutrition. 2012;36(2):197–204. doi:10.1177/0148607111413896

5. Ostermann M, Lumlertgul N, Mehta R. "Nutritional assessment and support during continuous renal replacement therapy." Seminars in Dialysis. 2021;34(6):449–456. doi:10.1111/sdi.12973

6. Mehta NM, Compher C. "A.S.P.E.N. Clinical Guidelines: Nutrition Support of the Critically Ill Child." JPEN. Journal of Parenteral and Enteral Nutrition. 2009;33(3):260–276. doi:10.1177/0148607109333114

7. Lorden H, Engelken J, Sprang K, et al. "Malnutrition in solid organ transplant patients: A review of the literature." Clinical Transplantation. 2023;37(11):e15138. doi:10.1111/ctr.15138

8. Nichols DC, Flannery AH, Magnuson BL, Cook AM. "Prealbumin Is Associated With in-Hospital Mortality in Critically Ill Patients." Nutrition in Clinical Practice. 2020;35(3):572–577. doi:10.1002/ncp.10414

9. Kim KG, Mishu M, Zolper EG, et al. "Nutritional markers for predicting lower extremity free tissue transfer outcomes in the chronic wound population." Microsurgery. 2023;43(1):51–56. doi:10.1002/micr.30794

10. Dellière S, Pouga L, Neveux N, et al. "Assessment of Transthyretin Cut-Off Values for a Better Screening of Malnutrition: Retrospective Determination and Prospective Validation." Clinical Nutrition. 2021;40(3):907–911. doi:10.1016/j.clnu.2020.06.017

11. McClave SA, DiBaise JK, Mullin GE, Martindale RG. "ACG Clinical Guideline: Nutrition Therapy in the Adult Hospitalized Patient." The American Journal of Gastroenterology. 2016;111(3):315–334. doi:10.1038/ajg.2016.28