Thyroxine-binding prealbumin (TBPA)

What sample is needed Sample for Thyroxine-Binding Prealbumin (TBPA)

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

What are the 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.

What are the 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.

How will you define Thyroxine-Binding prealbumin?

1. Thyroxine-binding prealbumin, also known as Transthyretin.
2. It binds thyroxine and retinol and transports them in the blood and CSF.
3. Thyroxine-binding prealbumin is a tetramer with a molecular weight of 50,000 D.
4. It is made of identical subunits with 127 amino acids.

How will you discuss the pathophysiology of Thyroxine-Binding Prealbumin (TBPA) and Prealbumin?

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 better 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 the other proteins, so clinical quantitation of the prealbumin is more valuable 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 if there is a zinc deficiency, prealbumin will be below.

What is the normal value of prealbumin and Tranthyretin?

Thyroxine-binding prealbumin (Transthyretin)

• Normal on protein electrophoresis   = 2% to 7%
• Prealbumin (Transthyretin)
  • <6 weeks = 4 to 36 mg/dL
  • >16 years = 13 to 27 mg/dL
  • Adult = 19.5 to 35.8 mg/dL:

Prealbumin:

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.

What are the causes of decreased levels of prealbumin?

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.

What are the causes of increased levels of prealbumin?

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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