This 54-kDa protein tetramer is synthesized in the liver, choroid plexus, CNS, placenta, intestine, pancreas, and meninges. It contains two binding sites for thyroid hormones T3 and T4 and two binding sites for serum retinol-binding protein. These different binding sites do not overlap. As a thyroid hormone transport and binding protein, transthyretin binds 10 " “15% of serum T3 and T4 for transport in the blood. In the CSF, where there is typically no albumin or thyroglobulin present, transthyretin serves as the only CSF-binding protein for T3 and T4. The presence of high concentrations of transthyretin in the CSF makes it a key indicator of leakage of the CSF into the sinus cavities, eyes, and ears when cranial trauma has occurred. Prealbumin is a negative acute-phase reactant. Other names: prealbumin (PA), thyroxine-binding prealbumin (TBPA).
Normal range: 18 " “40 mg/dL.
Use
Evaluation of nutritional status, total parenteral nutrition
Clinical indicator of liver status
Interpretation
Increased In
Chronic renal failure
Hodgkin disease
Decreased In
Inflammation
Hepatic dysfunction
Protein deficiency states
Cancer
CF
Chronic illness
Limitations
Anabolic steroids, corticosteroids, and androgens increase prealbumin levels.
Estrogens and oral contraceptives decrease prealbumin levels.
Zinc deficiency, acute alcohol intoxication, leakage of protein from damaged hepatic cells may cause a rise in the prealbumin levels.