Prealbumin
Also known as: Transthyretin, TTR
What Does Prealbumin Measure?
Prealbumin, also known as transthyretin (TTR), is a protein produced primarily by the liver that serves as a carrier for thyroid hormones (particularly thyroxine, T4) and retinol-binding protein, which transports vitamin A. Blood tests measure the concentration of this protein in the bloodstream, typically expressed in milligrams per deciliter (mg/dL). Unlike many other blood proteins, prealbumin has a very short half-life of only 2–3 days, making it an exceptionally sensitive and rapid indicator of changes in nutritional status and protein synthesis.
Why Does Prealbumin Matter?
Prealbumin is considered one of the most clinically valuable markers for assessing short-term nutritional status and protein malnutrition, particularly in hospitalized patients, the elderly, and individuals recovering from illness or surgery. Because it responds quickly to changes in protein and calorie intake, declining levels can signal nutritional deficiencies days before more traditional markers like albumin show changes. Low prealbumin levels are strongly associated with increased risk of complications, longer hospital stays, impaired wound healing, and higher mortality. It is also used to monitor conditions involving inflammation, liver disease, and rare genetic disorders such as transthyretin amyloidosis, where abnormal TTR protein deposits accumulate in organs.
Normal Ranges
Males
18–45 mg/dL
Females
18–45 mg/dL
Children
Varies by age; typically 10–30 mg/dL in infants, gradually increasing to adult levels by adolescence
Causes of High Levels
- Kidney disease (particularly chronic kidney disease or nephrotic syndrome with compensatory overproduction)
- High-dose corticosteroid therapy, which stimulates hepatic protein synthesis
- Anabolic steroid use, promoting increased protein production
- Hodgkin's lymphoma, which can paradoxically elevate transthyretin levels
- Adrenal insufficiency in some cases
- Excessive supplementation or overfeeding in clinical nutrition settings
Causes of Low Levels
- Protein-energy malnutrition or inadequate dietary protein intake
- Acute or chronic inflammation and infection (prealbumin is a negative acute-phase reactant)
- Liver disease or cirrhosis, reducing the liver's capacity to synthesize proteins
How to Improve Your Prealbumin
Diet
- Increase dietary protein intake to 1.2–1.5 g per kg of body weight daily, emphasizing complete protein sources such as eggs, lean meat, poultry, fish, and dairy
- Consume calorie-sufficient meals to prevent the body from using protein for energy rather than synthesis — aim for adequate total caloric intake before focusing on protein
- Include zinc-rich foods such as oysters, beef, pumpkin seeds, and legumes, as zinc is a cofactor in prealbumin synthesis
- Add vitamin A-rich foods like sweet potatoes, carrots, and leafy greens to support retinol-binding protein function alongside prealbumin
- Eat small, frequent meals if appetite is poor, especially during recovery from illness or surgery, to steadily supply amino acids for protein synthesis
Supplements
- Zinc: 8–11 mg/day (RDA) or up to 25–40 mg/day therapeutically under medical supervision to support hepatic protein synthesis
- High-quality protein supplements (whey or casein protein powders): 20–40 g per serving to meet daily protein targets, particularly for individuals with poor appetite or malabsorption
- Branched-chain amino acids (BCAAs): 5–10 g daily to support muscle protein synthesis and reduce catabolism during illness or recovery
Related Biomarkers
Frequently Asked Questions
What is the difference between prealbumin and albumin as nutritional markers?
Both albumin and prealbumin are liver-produced proteins used to assess nutritional status, but their key difference is their half-life. Albumin has a half-life of about 20 days, meaning it changes slowly and reflects long-term nutritional status over weeks to months. Prealbumin has a much shorter half-life of just 2–3 days, making it far more sensitive to recent changes in nutrition. This means prealbumin can detect nutritional deficiencies or improvements much sooner — making it especially useful for monitoring patients in hospitals or those undergoing nutritional therapy.
Can inflammation cause low prealbumin even if I am eating enough protein?
Yes, absolutely. Prealbumin is a 'negative acute-phase reactant,' meaning the liver deliberately reduces its production during inflammation or infection in order to redirect resources toward producing inflammatory response proteins like C-reactive protein (CRP) and fibrinogen. This means that during illness, surgery, or any inflammatory state, prealbumin levels can drop significantly even if protein and calorie intake is adequate. This is why clinicians often interpret prealbumin alongside CRP — if CRP is high, a low prealbumin may reflect inflammation rather than malnutrition alone.
What does it mean if my prealbumin is low on a blood test?
A low prealbumin level (below 18 mg/dL in adults) suggests either protein-energy malnutrition, active inflammation or infection, liver dysfunction, or a combination of these factors. Mild depletion is typically 10–17 mg/dL, moderate depletion is 5–9 mg/dL, and severe depletion is below 5 mg/dL. If your prealbumin is low, your healthcare provider will likely consider your recent diet, any ongoing illness, and other lab values like albumin, CRP, and liver function tests to determine the underlying cause and recommend appropriate treatment.