Prealbumin

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

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.