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Also known as transthyretin (TTR), it is a carrier protein produced mainly in the liver.
It also occurs in the brain , specifically in the choroid plexus, and in the retinal pigment epithelium in the eye. It binds with thyroxine (T4), which is the main hormone produced by the thyroid gland, and the retinol-binding protein, which in turn binds with retinol or vitamin A.
Clinical relevance of prealbumin
Why is prealbumin important and why is it clinically relevant?
It is relevant due to the short half-life, of course! The half-life of a substance is the time it takes for the concentration of that substance to fall to half its initial value.
Prealbumin’s short half-life makes it extremely sensitive to changes in the energy state of the body’s protein.
Albumin can’t even come close to this kind of precision. The half-life of albumin is around 20 days.
The importance of prealbumin in terms of energy requirements (think nutrition) is due to the liver, the main location where prealbumin is synthesized. Prealbumin degrades or begins to break down as fast as it is produced due to its short half-life.
The collapse inevitably leads to two clinically relevant effects:
- Accumulation of prealbumin cannot occur.
- Fluctuations in prealbumin levels are quickly detected.
Why get tested for prealbumin?
The reasons for ordering the prealbumin test are being reevaluated as the understanding of prealbumin evolves.
Historically, prealbumin has been ordered to help detect protein-calorie malnutrition and monitor the effectiveness of parenteral (eg, intravenous) nutrition.
The most recent evidence suggests that the reasons for changes in prealbumin levels may be more complex and the test should not be interpreted as a simple indicator of nutritional status.
Remember that prealbumin is a protein made by the liver. Your body uses it to make other proteins.
If your doctor suspects that you are not getting enough protein, he or she may order this test for a number of reasons:
- If you are elderly, you may want to know if you are getting enough nutrients from your diet.
- For a young child, a doctor can use this test to see if he is malnourished.
- If you plan to have surgery in a hospital, your doctor may order this test to see what types of nutritional support you will need during treatment.
Finally, your doctor might do a pre-albumin blood test if you have an eating disorder, to see how much protein you’ve lost.
If you are taking any medications, including over-the-counter medications, or if you are pregnant, you must notify your physician prior to your evaluation. All of these things can have an effect on the test results.
What do the results mean?
First, know that several things can affect your results. Each lab has a different way of taking this test, so the results differ from lab to lab. Talk to your doctor to find out for sure what your results mean.
In general, normal test results are as follows:
Adults: 15 to 36 milligrams per deciliter (mg / dL) or 150 to 306 milligrams per liter (mg / L).
Babies: 6 to 21 mg / dL for babies less than five days old.
Kids:
- From 1 to 5 years: from 14 to 30 mg / dL.
- Ages 6 to 9: 15 to 33 mg / dL.
- From 10 to 13 years: 22 to 36 mg / dL.
- From 14 to 19 years old: from 22 to 45 mg / dL.
Low levels can be caused by:
- Malnutrition.
- There is not enough zinc in your diet.
- Liver disease
- Cancer.
- Chronic illness.
- Inflammation or infection
- Digestive disorders
- Hyperthyroidism .
High levels can mean:
- Pregnancy.
- Renal problems.
- Hodgkin’s disease.
- Lack of iron.
- Overactive adrenal glands.
- Use of steroids.
- Alcoholism.
Whether your results are high or low, your doctor may order additional tests to help determine the reason for your abnormal prealbumin levels.
When to get tested?
There is no current consensus on when to get tested, although prealbumin may be ordered, along with nutritional intake assessments, when a healthcare professional suspects someone is malnourished or at risk of malnutrition.
