transthyretin(redirected from ttr)
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1. A protein component of plasma having a molecular weight of about 55,000 and containing 1.3% carbohydrate; estimated plasma concentration is 0.3 g per 100 mL; abnormal levels of prealbumin are found in cases of familial amyloidosis. Synonym(s): transthyretin
2. The protein-containing zone observed in zone electrophoresis of serum that migrates more rapidly than serum albumin.
transthyretinPrealbumin A 55 kD homotetrameric protein that binds thyroxine and retinol; transthyretin is ↓ in malnutrition and in acute and chronic inflammation, and thus is considered a 'negative acute phase protein', which may be defective in AD amyloidosis. Cf Proalbumin.
To assess nutritional status and evaluate liver function toward diagnosing disorders such as malnutrition and chronic renal failure.
SpecimenSerum (1 mL) collected in a gold-, red-, or red/gray-top tube.
|Age||Conventional Units||SI Units (Conventional Units × 10)|
|Newborn–1 mo||7–39 mg/dL||70–390 mg/L|
|1–6 mo||8–34 mg/dL||80–340 mg/L|
|6 mo–4 yr||2–36 mg/dL||20–360 mg/L|
|5–6 yr||12–30 mg/dL||120–300 mg/L|
|7 yr–adult/older adult||12–42 mg/dL||120–420 mg/L|
Prealbumin is a protein primarily produced by the liver. It is the major transport protein for triiodothyronine and thyroxine. It is also important in the metabolism of retinol-binding protein, which is needed for transporting vitamin A (retinol). Prealbumin has a short biological half-life of 2 days. This makes it a good indicator of protein status and an excellent marker for malnutrition. Prealbumin is often measured simultaneously with transferrin and albumin.
This procedure is contraindicated for
Evaluate nutritional status
- Alcoholism (related to leakage of prealbumin from damaged hepatocytes and/or poor nutrition)
- Chronic renal failure (related to rapid turnover of prealbumin, which reflects a perceived elevation in the presence of overall loss of other proteins that take longer to produce)
- Patients receiving steroids (these drugs stimulate production of prealbumin)
- Acute-phase inflammatory response (prealbumin is a negative acute-phase reactant protein; levels decrease in the presence of inflammation) Diseases of the liver (related to decreased ability of the damaged liver to synthesize protein) Hepatic damage (related to decreased ability of the damaged liver to synthesize protein) Malnutrition (synthesis is decreased due to lack of proper diet) Tissue necrosis (prealbumin is a negative acute-phase reactant protein; levels decrease in the presence of inflammation)
- Drugs that may increase prealbumin levels include anabolic steroids, anticonvulsants, danazol, oral contraceptives, prednisolone, prednisone, and propranolol.
- Drugs that may decrease prealbumin levels include amiodarone and diethylstilbestrol.
- Fasting 4 hr before specimen collection is highly recommended. Reference ranges are often based on fasting populations to provide some level of standardization for comparison. The presence of lipids in the blood may also interfere with the test method; fasting eliminates this potential source of error, especially if the patient has elevated lipid levels.
Nursing Implications and Procedure
- Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
- Patient Teaching: Inform the patient this test can assist in assessing nutritional status.
- Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
- Obtain a history of the patient’s endocrine, gastrointestinal, and hepatobiliary systems; symptoms; and results of previously performed laboratory tests and diagnostic and surgical procedures.
- Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
- Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
- Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
- Instruct the patient to fast for 4 hr before specimen collection.
- Note that there are no fluid or medication restrictions, unless by medical direction.
- Potential complications: N/A
- Ensure that the patient has complied with dietary restrictions; ensure that food has been restricted for at least 4 hr prior to the procedure.
- Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
- Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
- Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
- Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
- Promptly transport the specimen to the laboratory for processing and analysis.
- Inform the patient that a report of the results will be made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
- Instruct the patient to resume usual diet, as directed by the HCP.
- Nutritional Considerations: Nutritional therapy may be indicated for patients with decreased prealbumin levels. Educate the patient, as appropriate, that good dietary sources of complete protein (containing all eight essential amino acids) include meat, fish, eggs, and dairy products and that good sources of incomplete protein (lacking one or more of the eight essential amino acids) include grains, nuts, legumes, vegetables, and seeds.
- Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
- Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
- Related tests include albumin, chloride, ferritin, iron/TIBC, potassium, protein, sodium, T4, T3, transferrin, and vitamin A.
- Refer to the Endocrine, Gastrointestinal, and Hepatobiliary systems tables at the end of the book for related tests by body system.