Prealbumin (Transthyretin)
A protein made by the liver that carries thyroid hormone and a vitamin A complex. It falls with inflammation, so it is a weak guide to nutrition on its own.
AI-verified against cited sources. Awaiting expert reviewAlso called PAB, TTR, TBPALOINC 14338-8
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What it is
Prealbumin, also called transthyretin, is a protein made by the liver. It carries thyroid hormone and a protein bound to vitamin A through the blood. It breaks down quickly, with a half-life of about 2 days, so the level can change within days. For years it was used to check protein nutrition, but it also falls when the body is inflamed. Today it is read with care.
Why it matters
A low prealbumin can go with poor protein and calorie intake, but it can also reflect infection, injury, surgery or long-term illness. A major nutrition society (ASPEN) says prealbumin tracks inflammation rather than nutrition status and should not be used alone as a nutrition marker. Some clinicians still follow it in people who are very sick or in hospital. It does not replace a full look at your eating, weight and health.
If it’s low
A low prealbumin has many possible causes. Inflammation, illness and injury are common reasons, and low food intake can be one too. A low result alone does not show that you are malnourished, and your clinician will read it with your symptoms, weight and other tests.
Common causes
- Inflammation, serious infection or recent surgery
- Injury or burns
- Serious or long-term illness, including cancer
- Not getting enough protein and calories, or trouble absorbing nutrients
- Liver disease
- Overactive thyroid (hyperthyroidism)
- Certain digestive diseases
What can help
- Ask whether inflammation or illness is the likely reason, and whether the test should be repeated once you have recovered
- Talk with your clinician or a registered dietitian about your overall nutrition, rather than trying to raise this one number
- Mention any unplanned weight loss, weakness or trouble eating
If it’s high
A higher prealbumin is not usually a problem, and the test is not used to diagnose the conditions linked to it. Your clinician can put a higher result in context.
Common causes
- High-dose corticosteroid medicines
- Kidney failure
- Alcohol use disorder
- Hodgkin lymphoma
What can help
- Review your medicines with your clinician, including any steroids
- Ask whether your kidney function needs a closer look if the result is well above the range
Usual ranges
What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.
See Prealbumin by age and sex, with the U.S. survey numbers where they exist.
What can affect your result
- Inflammation, infection, injury and surgery lower it (it is a negative acute-phase protein)
- Liver disease lowers it, because the liver makes it
- Corticosteroid medicines and kidney failure can raise it
- Age and sex: children and teens have a different range from adults, healthy men average higher than women, and levels tend to fall after about age 60 (Ingenbleek 2015)
- Pregnancy can change levels
- Overactive thyroid can lower it
- Inflammation, infection, injury or surgery can lower the result for reasons unrelated to what you eat.
- Some medicines can change results, including high-dose corticosteroids (which can raise it). Tell your clinician everything you take, and do not stop any medicine unless your clinician says so.
- Pregnancy can change levels (MedlinePlus).
Prealbumin has a half-life of about 2 days, so it can move within days, much faster than albumin.
When to talk to a clinician
No urgent prealbumin value has been published by the large reference labs that were checked. See a clinician if a low result comes with unplanned weight loss, weakness, dizziness, feeling cold, hair loss or dry skin, trouble eating, ongoing vomiting or diarrhea, or swelling. If you have trouble breathing, chest pain, confusion or fainting, call 911 or your local emergency number.
Questions you could ask
- Is prealbumin useful for my situation, or are other measures better?
- How does it fit with my albumin and other results?
- Could any of my medicines, such as steroids, explain a higher result?
- Does my kidney function matter for this result?
- Could inflammation or a recent illness explain this result?
- Should we recheck it after I recover?
Questions people ask
Is prealbumin the same as albumin?
No. They are different proteins made by the liver. Prealbumin lasts about 2 days in the blood, while albumin lasts much longer, so prealbumin changes faster.
Does a low prealbumin mean I am malnourished?
Not by itself. Inflammation, infection, surgery and liver disease can all lower it, even when you are eating well. Your clinician will look at your weight, intake and other tests along with this number.
Why do some doctors no longer order prealbumin?
A 2021 position paper from a major nutrition society (ASPEN) concluded that prealbumin reflects inflammation more than nutrition. Some clinicians still follow it in people who are very ill or in hospital.
Show the science and sources
Units
- 1 mg/dL = 1 mg/dL
- 1 mg/dL = 0.01 g/L
- 1 mg/dL = 10 mg/L
Open the Prealbumin unit converter
Is a change real?
Prealbumin naturally varies about 10.9% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 34% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: Desirable Biological Variation Database specifications, 2014 update (Minchinela J, Ricos C, et al.; the 'Ricos database', a compilation of median published CVI/CVG).
For clinicians and researchers
Transthyretin (TTR) is a 55 kDa non-glycosylated homotetramer of 127-residue subunits, made in the liver. In plasma it circulates mostly bound to retinol-binding protein 4 with its retinol, and it carries a minor share of thyroxine. Its half-life is about 2 days (retinol-binding protein 4: about 0.5 day). Because of its short half-life and small pool it responds quickly to changes in hepatic synthesis, and it is a negative acute-phase reactant. The ASPEN position paper (Evans 2021) concludes that albumin and prealbumin characterize inflammation rather than nutrition status or protein-energy malnutrition and should not be used as nutrition markers. Other authors argue that TTR tracks lean body mass and the balance of energy and protein intake (Ingenbleek and Bernstein 2015), so the debate is not closed. Reference intervals differ with assay and lab: Labcorp 14 to 35 mg/dL in adults, ABIM 16 to 30 mg/dL. Assays are immunoturbidimetric or nephelometric. This is a different test from genetic testing of the TTR gene for hereditary transthyretin amyloidosis.
LOINC 14338-8 (primary), 46130-1, 6793-4. Specimen: serum-or-plasma.
Sources
- Prealbumin (test 016931) sample report, Labcorp
- Pediatric Testing Reference Ranges (Prealbumin, test 016931), Labcorp
- ABIM Laboratory Test Reference Ranges, January 2026, American Board of Internal Medicine (2026)
- Prealbumin Blood Test, MedlinePlus (National Library of Medicine)
- The Use of Visceral Proteins as Nutrition Markers: An ASPEN Position Paper, Nutrition in Clinical Practice (ASPEN) (2021)
- Plasma Transthyretin as a Biomarker of Lean Body Mass and Catabolic States, Advances in Nutrition (2015)
- LOINC 14338-8, 46130-1 and 6793-4 (NLM Clinical Tables), National Library of Medicine
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.