The pre-albumin assay is an in vitro assay used for the for the quantitative determination of pre-albumin in human serum. Pre-albumin, also known as transthyretin, is a protein produced by the liver. Its main functions are to transport thyroid hormone, thyroxine, and vitamin a through the body. While pre-albumin is produced primarily by the liver, it is also produced by other parts of the body including the choroid plexus in the brain, pancreatic islet cells in the embryonic sac, and by enterochromaffin cells in the gastrointestinal mucosa.
Pre-albumin has long been used in determining nutritional status of patients. Malnutrition is associated with increased complications in hospitalized patients and increased cost in healthcare. Pre-albumin has been considered one of the best markers for malnutrition because it is relatively easy to determine on instrumentation and unlike other proteins, it is not as affected by liver disease. It will likely decrease with liver failure and may increase during kidney failure. Pre-albumin may also be elevated with use of steroids and alcoholism. Pre-albumin is also unaffected by hydration status. Pre-albumin is also often preferred over albumin because it has a shorter half-life, therefore changes in pre-albumin are more reflective of the body’s nutrition. Pre-albumin may also be helpful in evaluating patients that are hospitalized and chronically or critically ill. Lower pre-albumin levels may indicate malnutrition. Low pre-albumin may serve as a predictor for medical outcomes, like complications with patients who suffer from anorexia nervosa. Evaluation of pre-albumin may also indicate other conditions like hypermetabolism or malabsorption. Recent findings do also indicate that pre-albumin changes in patients can also be related to other issues like inflammation, infection, or trauma. Pre-albumin changes may be affected by inflammation in particular, because inflammatory signals can inhibit protein synthesis, so it may be helpful to assess nutrition using pre-albumin in tandem with other testing. Pre-albumin may also change in response to hormone treatment.
At Solaris Diagnostics, pre-albumin is measuring using an immunoturbidimetric method. The serum sample is incubated with an assay buffer and then a reagent that has antibodies for human pre-albumin is added. The complex that forms from this increases the turbidity of the solution. The instrument then reads the absorbance of the solution, which is used to calculate the pre-albumin. Solaris Diagnostics can provide pre-albumin results within 24 hours from the time the sample is received in the laboratory.