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Transthyretin; tryptophan-rich prealbumin; thyroxine-binding prealbumin
Prealbumin was traditionally used to diagnose patients with malnutrition and to monitor patients at risk of poor nutrition. Recent research suggests that prealbumin is more complex than previously thought and requires more investigation.
There is no clear guideline for when to test prealbumin however it may be ordered if your doctor suspects you are malnourished; if you are about to be admitted to the hospital for surgery; if you are hospitalised with certain diseases; or if you are having parenteral (artificial) nutrition or kidney dialysis.
A blood sample drawn from a vein in the arm
The test measures levels of prealbumin, an important protein found in the blood. Prealbumin is produced primarily by the liver. It serves as a source for the production of other proteins, and carries substances in the blood such as the thyroid hormone thyroxine. Prealbumin has a half-life of only two days, which means that it breaks down quickly in the body and the amount in the blood changes quickly, decreasing when there is protein deficiency. The level of prealbumin can be affected by inflammation making it difficult for doctors to interpret in some cases.
A blood sample is taken by a needle from a vein in the arm.
No test preparation is needed.
Until recenty the prealbumin test was used to help diagnose problems with nutrition in particular 'protein-calorie' malnutrition. In this condition, which can affect more than 30% of hospitalised patients, the body breaks down muscle, protein and body fat. This type of malnutrition can lead to complications and even death if not treated. Children with malnutrition may fail to thrive or have stunted growth.
While some doctors still use this test to diagnose and monitor malnutrition it is now thought that changes in prealbumin can be due to inflammation and that the test may not accurately reflect nutritional status.
Keeping in mind the new research into this test, a doctor may request a prealbumin test when signs of malnutrition or poor nutrition are present. Signs of malnutrition include extreme 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 or albumin test may also be requested prior to surgery or when a patient is being treated for certain conditions. Doctors may also use the test regularly to monitor patients who have had low prealbumin results and to evaluate the effectiveness of treatment.
A person’s prealbumin level is dependent according to their age and gender.
A low level of prealbumin may be seen with:
Low levels of prealbumin are also seen with inflammation. If a patient has inflammation, it is impossible to know exactly what the prealbumin value means. When inflammation and malnutrition are both present, prealbumin levels fall very far, very quickly.
A high level of prealbumin may be seen in certain conditions such as:
Certain medications can also lower your prealbumin level, including amiodarone, oestrogens and oral contraceptives (the pill).
Medications that can cause your prealbumin level to rise in your blood are anabolic steroids, androgens (male hormones) and prednisolone.
Albumin (in blood) and microalbumin (in urine) are the same molecule, however prealbumin, despite the similar-sounding name, is a completely unrelated molecule. Albumin testing is more often used to test for liver or kidney disease or to learn if your body is not absorbing enough amino acids. Albumin can also be used to monitor nutritional status and is a more widely available test than prealbumin. The microalbumin, more correctly termed the albumin/creatinine ratio test, measures very small levels of albumin in your urine and may indicate whether you are at risk for developing kidney disease.
RCPA Manual: Albumin
Healthdirect Australia: Malnutrition
Last Review Date: February 1, 2018