Thyroxine-binding prealbumin (TBPA)

Sample for Thyroxine-Binding Prealbumin (TBPA)

1. The venous blood of the patient is needed to prepare the serum.
2. This can be estimated in the 24 hours of urine and CSF.

Indications for Thyroxine-Binding Prealbumin (TBPA)

1. Marker for the patient with nutritional status.
2. It is a sensitive indicator of protein synthesis and catabolism.

Precautions for Thyroxine-Binding Prealbumin (TBPA)

1. Avoid hemolysed and lipemic serum.
2. In the case of coexistent infection, the results are not reliable.
3. Anabolic steroids, androgens, and prednisone increase the level.
4. Amiodarone, oral contraceptives, and estrogens decrease the level.

Pathophysiology of Thyroxine-Binding Prealbumin (TBPA)

1. Prealbumin is the major plasma protein.
2. Prealbumin has a shorter half-life of 2 days.
   1. The Prealbumin half-life of 2 days is much less than the albumin of 21 days.
3. This is present in the serum and CSF.
   1. This is the main component of the CSF proteins.
4. The pre-albumin binds:
   1. Retinol (RBP) also binds the vit. A.
   2. Prealbumin binds the thyroxin called thyroxine-binding prealbumin (TBPA).
5. This is a good marker than albumin and transferrin.
6. This is a better indicator of synthetic liver activity.
   1. Prealbumin levels fluctuate more rapidly in response to liver synthesis rate than do the other proteins, so clinical quantitation of the prealbumin is more useful as a marker of the nutritional status.
   2. Because of the shorter half-life, it is a better indicator of any change affecting protein synthesis and catabolism. 
   3. This is advised to monitor the effectiveness of total parenteral nutrition. 
7. Prealbumin decreases acute and chronic inflammation.
   1. Prealbumin is a negative acute-phase reactant protein.
   2. Its level decreases in malignancy and inflammation.
   3. Also, it decreases the protein-losing disease of the intestine and kidneys.
8. Zinc is needed for its synthesis, so in case of a deficiency of Zinc, prealbumin will be below.

Normal

Source 2

1. Adult = 15 to 36 mg/dL.
2. Child:
   1. <  5 days =6 to 21 mg/dL
   2. 6 to 9 years = 15 to 33 mg/dL.
   3. 10 to 13 years = 22 to 36 mg/dL.
   4. 14 to 19 years = 22 to 45 mg/dL.
3. Urine 24 hours = 0.017 to 0.047 mg/ 24 hours.
4. CSF = 2% of the total CSF proteins.

The decreased level of prealbumin is seen in the following:

1. In hepatocellular dysfunction.
2. It is decreased in tissue damage.
3. In inflammation.
4. In malnutrition.
5. In burn.
6. Drugs like oral contraceptives, Estrogen, and amiodarone.
   1. Salicylates poisoning.

The increased level of prealbumin is seen in the following:

1. In Hodgkin’s disease.
2. In chronic kidney diseases.
3. Some cases of nephrotic syndrome.
4. In pregnancy
5. Drugs like steroids, prednisolone, and androgens.

• Critical value = when <10.7 mg/dL
  • This indicates severe nutritional deficiencies.

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