Type of test Blood; urine (24-hour); cerebrospinal fluid (CSF) analysis
Normal findings
Serum Adult/elderly: 15-36 mg/dL or 150-360 mg/L (SI units)
Child
- < 5 days: 6-21 mg/dL
- 1-5 years: 14-30 mg/dL
- 6-9 years: 15-33 mg/dL
- 10-13 years: 22-36 mg/dL
- 14-19 years: 22-45 mg/dL
Urine (24-hour) : 0.017-0.047 mg/day
CSF: Approximately 2% of total CSF protein
Possible critical values: Serum prealbumin levels less than 10.7 mg/dL indicate severe nutritional deficiency.
Test explanation and related physiology
Prealbumin is one of the major plasma proteins. Because pre albumin can bind thyroxine, it is also called thyroxine- binding prealbumin (TBA). However, prealbumin is secondary to thyroxine-binding globulin in the transportation of triiodothyronine (T3) and thyroxine (T4). Prealbumin also plays a role in the transport and metabolism of vitamin A.
Because prealbumin levels in serum fluctuate more rapidly in response to alterations in synthetic rate than do those of other serum proteins, clinical interest in the quantification of serum prealbumin has centered on its usefulness as a marker of nutritional status. Its half-life of 1.9 days is much less than the 21-day half-life of albumin. Because prealbumin has a short half-life, it is a sensitive indicator of any change affecting protein synthesis and catabolism. For this reason, prealbumin is frequently ordered to monitor the effectiveness of total parenteral nutrition (TPN).
Prealbumin is significantly reduced in hepatobiliary disease because of impaired synthesis. Prealbumin is also a negative acute phase reactant protein; serum levels decrease in inflammation, malignancy, and protein-wasting diseases of the intestines or kidneys. Because zinc is required for synthesis of prealbumin, low levels occur with a zinc deficiency. Increased levels of prealbumin occur in Hodgkin disease and chronic kidney disease.
Interfering factors
• Coexistent inflammation may make the interpretation of test results impossible.
* Drugs that may cause increased levels include anabolic steroids, androgens, and prednisolone.
* Drugs that may cause decreased levels include amiodarone, estrogens, and oral contraceptives.
Procedure and patient care
• See inside front cover for Routine Blood Testing.
• Fasting: no
• Blood tube commonly used: red
• If the patient is going to collect a 24-hour urine specimen, provide a collection bottle. (See guidelines on inside front cover.)
Abnormal findings
Increased levels
- Some cases of nephrotic syndrome
- Hodgkin disease
- Chronic kidney disease
- Pregnancy
Decreased levels
- Malnutrition
- Liver damage
- Burns
- Salicylate poisoning
- Inflammation
- Infection
