Sample for Prealbumin
- This is done on the fresh serum of the patient.
- 24 hours of the urine sample can also be tested.
Indications for Prealbumin
- It is used to assess nutritional status.
- As workup in patients with kidney diseases.
- Advised in subclinical deficit and assessing the response to restorative therapy.
Precautions for Prealbumin
- In the case of inflammation, the result is not representative of the disease.
- Drugs like anabolic steroids, androgens, and prednisolone increase the level.
- Drugs like estrogens and oral contraceptives decrease the level.
Pathophysiology of Prealbumin
- Prealbumin is synthesized mainly in the liver.
- This was also called transthyretin because of its binding with thyroid hormones.
- This is the fastest-moving protein on serum electrophoresis.
- This has the same concentration in the serum and CSF. Due to the low level of other proteins in the CSF, prealbumin is the major protein in the CSF.
- This can be used to differentiate CSF leakage from the nasal secretions and the fracture of the base of the skull.
- A very faint band is normally not seen on traditional electrophoresis.
Prealbumin is a carrier protein:
- It binds to T3 and T4, so-called Transthyretin or thyroxine-binding prealbumin.
- This is also referred to as thyroxine-binding prealbumin (TBPA).
- It also binds and carries retinol as a retinol-binding protein, which binds Vitamin A.
- This protein-vitamin complex is essential for transporting oil-soluble Vitamin A in the body.
- Zinc is required to synthesize prealbumin; low levels occur in Zinc deficiency.
Functions of prealbumin:
- This is also the amyloid precursor protein found in cardiac amyloidosis.
- It has a half-life of 48 hours (1.9 days), which increases its importance superior to Albumin and transferrin.
- Albumin’s half-life is 21 days.
- Prealbumin is a good indicator of any change affecting protein synthesis and catabolism.
- Because of its short half-life (2 days), prealbumin responds quickly to nutritional intake and nutritional restoration.
- It gives the current nutritional status of the body, not the status from 3 weeks ago.
- It can cross the blood-brain barrier and actively secrete into the cerebrospinal fluid and choroid plexus.
- Importance of prealbumin in the nasal secretions to differentiate fluid coming from the skull fracture versus nasal secretion.
Negative acute-phase protein:
- Prealbumin is a negative acute-phase protein, and serum level decreases in inflammation, malignancy, and protein-losing diseases of the kidneys and intestine.
Protein status of the patients by estimation of prealbumin:
|The severity of the malnutrition||Prealbumin level|
|Mild||10 to 15 mg/dL (100 to 150 mg/L)|
|Moderate||5 to 10 mg/dL (50 to 100 mg/L)|
|Severe||0 to 5 mg/dL (0 to 50 mg/L)|
The normal level of prealbumin
|Adults/elders||15 to 36 mg/dL (150 to 360 mg/L)|
|<5 years||6 to 21 mg/dL|
|1 to 5 years||14 to 30 mg/dL|
|6 to 9 years||15 to 33 mg/dL|
|10 to 13 years||22 to 36 mg/dL|
|14 to 19 years||22 to 45 mg/dL|
|Urine 24 hours sample||0.017 to 0.047 mg/day|
|CSF||Approximately 2% of the CSF total proteins|
|Critical value||<10.7 mg/dL (indicates severe malnutrition|
- 19 to 38 mg/dL (190 to 380 mg/L) by nephelometry
Interpretations of Prealbumin for nutritional status:
- In severe protein deficiency, = Level is 0 to 5 mg/dl.
- In moderate protein deficiency, = Level is 5 to 10 mg/dl.
- In mild protein deficiency, = Level is 10 to 15 mg/dl.
- (Normal value may vary from lab to lab.)
The increased level is seen in the following:
- Chronic Alcoholics.
- Patients with corticosteroid therapy.
- Hodgkin’s lymphoma.
- Kidney diseases.
The decreased level is seen in the following:
- In cases of malnutrition.
- Liver diseases.
- Inflammatory conditions.
- In cases of trauma like burns.
- In chronic diseases.
- In some digestive diseases.
- In Cancers.
- Salicylate poisoning.