Prealbumin, also called transthyretin, is one of the major proteins in the blood and is produced primarily by the liver. Its functions are to carry thyroxine (the main thyroid hormone) and vitamin A throughout the body.
Until recently, the prealbumin test was believed to be a useful marker of nutritional status and was used to help detect and diagnose protein-calorie malnutrition as well as to monitor people receiving total parenteral nutrition (TPN, getting nutrition via a solution injected into a vein). It was also used to monitor changes in nutritional status in someone undergoing hemodialysis as part of treatment for kidney disease.
Some healthcare practitioners continue to use the test in this manner; however, there is controversy because changes in prealbumin may actually reflect other conditions such as inflammation, infection, or trauma. As such, it has been suggested by some health professionals that the prealbumin test should no longer be used to assess nutritional status or diagnose malnutrition. However, others believe that the test can be useful in determining prognosis for people who are critically ill, hospitalized, and/or at risk of poor outcomes and can prompt nutritional and other support that may improve patient outcomes.
Although the names are similar, prealbumin and albumin are completely different molecules. They are both proteins made by the liver, however, and both have been used historically to evaluate nutritional status. Serum/plasma (or blood) albumin is now more often used to screen for and help diagnose liver or kidney disease and is tested on a blood sample. The urine albumin test (in the past, called a microalbumin test) detects and measures albumin in the urine as an early indicator of kidney damage.
A low level of prealbumin may be seen with:
- Severe or chronic illness
- Trauma, such as burns
- Liver disease
- Serious infections
- Certain digestive disorders
- Given the ongoing discussion of the appropriate use of this test as researchers continue to explore the role of prealbumin in the body and what changes in its level in the body reflect, interpretation of prealbumin results is challenging. Some suggest that a single prealbumin result is less meaningful that a series of measurements taken several days apart, along with other clinical assessments and laboratory tests. For example, measures of inflammation, such as C Reactive Protein (CRP), may be ordered to aid in interpretation of the prealbumin results.
- Drugs such as amiodarone, estrogens, and oral contraceptives (birth control pills) can decrease prealbumin levels.
A high level of prealbumin may be seen in certain conditions, but the test is not used for diagnosis or monitoring in these situations.
- Anabolic steroids, androgens, prednisolone, and high-dose non-steroidal anti-inflammatory medications can increase prealbumin concentrations.
- Prealbumin levels can also be high in Hodgkin disease, kidney failure, iron deficiency, pregnancy, and with hyperactive adrenal glands.
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