What this test measures
Prealbumin (transthyretin) is a small protein made by the liver that transports thyroid hormone (T4) and works with retinol-binding protein to carry vitamin A. Its short half-life (~2 days, vs 21 days for albumin) makes it a fast-changing marker of liver synthetic activity, recent protein-calorie intake, and acute inflammation.
It was historically used as a "nutrition marker" — falling rapidly with poor intake and rising with refeeding. Current ASPEN (American Society for Parenteral and Enteral Nutrition) guidance, however, advises caution: prealbumin (and albumin) are now considered "negative acute-phase reactants" that fall during inflammation regardless of nutritional intake. They reflect inflammation more than nutrition.
Why it matters
In Indian hospitals, prealbumin is sometimes used in ICU and nutrition rounds to track short-term protein status. A rapidly falling prealbumin can signal worsening illness, persistent inflammation or inadequate caloric intake; a rising prealbumin during recovery suggests resolving inflammation and improving anabolism. ASPEN no longer recommends using prealbumin alone to diagnose malnutrition — clinical assessment (weight history, muscle mass, intake, functional status) is preferred.
Outside ICU and nutrition use, prealbumin can be raised in nephrotic syndrome (liver compensation), Hodgkin lymphoma and some genetic variants; low in chronic liver disease, acute infection, surgery, burns, and inflammatory states.
How to prepare
No fasting required. Mention any recent surgery, infection, or steroid use. Continue regular medications.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Prealbumin (mg/dL)[1][2] | 20 – 40 | Low prealbumin — acute illness / inflammation, chronic liver disease, severe protein-calorie undernutrition, infection, surgery, burns, nephrotic syndrome (some patterns), hyperthyroidism. Interpret with CRP — low prealbumin with high CRP usually reflects inflammation rather than pure malnutrition. | High prealbumin — uncommon. Can be seen in some genetic variants, alcoholism (early), severe nephrotic syndrome (liver upregulation), Hodgkin's disease, or anabolic steroid use. |
Prealbumin vs Albumin — half-life matters
| Marker | Half-life | Best use | Caution |
|---|---|---|---|
| Albumin | ~ 21 days | Reflects chronic liver function, chronic disease state | Falls with inflammation; not a pure nutrition marker |
| Prealbumin (transthyretin) | ~ 2 days | Reflects recent (days) changes — useful in ICU and recovery tracking | Also negative acute phase reactant — falls with inflammation |
| Retinol-Binding Protein | ~ 12 hours | Very rapid changes — research mostly | Very sensitive to inflammation |
| CRP | Hours to days | Inflammation marker | Used alongside prealbumin to interpret it correctly |
Frequently asked questions
Is prealbumin a nutrition test?
It used to be marketed that way. Current ASPEN guidance says it is more an inflammation marker than a pure nutrition marker. It falls in inflammation regardless of intake. Trends in prealbumin during recovery can still be useful, but a single low value should not be used to label someone malnourished.
Do I need to fast?
No fasting required.
Why is prealbumin sometimes preferred over albumin?
Its short half-life (~2 days) means it responds to changes in protein status within days, while albumin takes weeks. In an ICU patient where you want to see if the nutrition plan is working, prealbumin moves first.
How is prealbumin used in ICU?
Some units track it weekly during prolonged ICU stays — rising prealbumin alongside falling CRP suggests recovery; persistently low prealbumin in a patient on adequate nutrition often reflects ongoing inflammation, not the diet.
Can low prealbumin alone diagnose malnutrition?
No. ASPEN guidance now relies on clinical criteria (weight loss, muscle mass, intake, functional status) rather than lab markers. Prealbumin can support an assessment but should not stand alone.
What raises prealbumin?
Recovery from acute illness, resolving inflammation, hyper-anabolic states, some genetic variants, Hodgkin lymphoma, severe nephrotic syndrome.
Is prealbumin related to TTR amyloidosis?
Yes — transthyretin (TTR) is the same protein. In TTR amyloidosis, an abnormal TTR misfolds and deposits in tissues, causing cardiac and neurological disease. Diagnosis is by genetic testing and tissue biopsy, not serum prealbumin level.
Related Other / Biochemistry tests
Tests commonly ordered alongside PREALBUMIN, or that help interpret an unexpected result.
Sources & references
- NIH MedlinePlus — Prealbumin Blood Test · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Prealbumin · accessed 2026-05-30T00:00:00.000Z
- ASPEN — Nutrition Assessment Recommendations · accessed 2026-05-30T00:00:00.000Z
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