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Prealbumin

Also known as: PA; Tryptophan-rich prealbumin; Thyroxine-binding prealbumin; TBPA
Formal name: Transthyretin test
Related tests: Albumin; Transferrin

The Test

How is it used?

Prealbumin is ordered to help doctors detect and diagnose protein-calorie malnutrition in people who are critically or chronically ill and/or are at an increased risk for malnutrition. Protein deficiencies can occur with inadequate availability of dietary protein, decreased ability to digest protein, increased protein loss, and with increased protein requirements. They can affect the body's ability to heal, to fight infection, and can increase the risk of complications. With protein-calorie malnutrition, the body begins to break down muscle, protein, and body fat. Children with malnutrition may fail to thrive or have stunted growth.

The prealbumin test is ordered to make an assessment of nutritional status:

  • Before a scheduled surgery
  • In patients who are hospitalized with certain conditions
  • In patients who are chronically ill

Many people have a decline in nutrition during their hospital stay, especially after surgery. Studies have shown that good nutrition prior to surgery helps to avoid complications, such as pneumonia and infection, after surgery. If the prealbumin test indicates that someone is malnourished or has a poor nutritional status, then corrective measures can be taken before surgery and periodic prealbumin tests can be ordered as necessary after surgery to monitor the person's status.

The prealbumin test may also be ordered to monitor changes in people who are receiving parenteral nutrition, such as intravenous treatment. It may be ordered to monitor changes in nutritional status in someone who is receiving hemodialysis, as part of treatment for kidney disease.

A prealbumin test may be ordered by itself or along with other tests such as albumin and transferrin to evaluate nutritional status. The prealbumin test is not available in every laboratory; for this reason, an albumin test may sometimes be ordered instead of a prealbumin.

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When is it ordered?

A doctor orders a prealbumin test when signs of malnutrition or poor nutrition are present or when a person is at risk for protein deficiency. Signs of malnutrition include unintended weight loss, stunted growth in a child, weakened resistance to infection, or being unable to think clearly. Hair may become brittle or begin to fall out, the skin may be dry or yellowish, muscles may feel weak, and fainting spells may occur. In younger women, menstrual periods may stop.

A prealbumin and/or albumin test may be ordered prior to surgery and whenever someone is being treated for a chronic or critical illness that may cause malnutrition. A doctor may order a prealbumin periodically to monitor someone with a low prealbumin result and to evaluate the effectiveness of treatment.

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What does the test result mean?

Looking for reference ranges?

The prealbumin measurement reflects the current state of a person's nutrition. If prealbumin is low, other proteins and nutrients in the blood may also be low.

Decreased concentrations of prealbumin may be seen in patients with:

Low levels of prealbumin are also seen with inflammation. When inflammation and malnutrition are both present, prealbumin levels can rapidly fall to very low levels and their interpretation can be more difficult. 

Increased concentrations of prealbumin may be seen in people with:

  • High-dose corticosteroid therapy
  • Hyperactive adrenal glands
  • High-dose nonsteroidal anti-inflammatory medications
  • Hodgkin's disease
  • Kidney failure

The prealbumin test is not typically used to monitor these conditions.

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Is there anything else I should know?

Drugs such as amiodarone, estrogens, and oral contraceptives (birth control pills) can decrease prealbumin levels.

Anabolic steroids, androgens, and prednisolone can increase prealbumin concentrations.

Recent research has shown that the prealbumin test can predict poor outcomes for hemodialysis patients. A low initial reading (baseline level) of prealbumin predicts that a patient may have an increased risk for complications, and steadily dropping prealbumin values are associated with low survival.

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