Acute Phase Protein – Part 7 – Albumin and Prealbumin
Acute-phase protein (Acute Phase Reactants)
- Acute-phase protein is raised in inflammatory conditions.
- When there is an increase in a protein called positive acute-phase protein.
- In the case of a decrease in the acute phase protein, is called negative phase protein.
- The acute phase proteins (positive) are protein whose concentration increases in the plasma and after the disease episode is over then it decreases and may become normal.
Albumin
Sample
- The venous blood of the patient is needed to prepare the serum.
- Try to analyze the fresh sample.
- Can store at 4 °C for <72 hours.
- The serum is stable at -20 °C for 6 months.
Precaution
- Avoid hemolysed and lipemic serum.
- A prolonged tourniquet can raise the level of albumin and other proteins.
- Blood from the side of the I/V drip will dilute the sample.
Indication
- In renal diseases.
- In liver diseases.
- In protein-losing enteropathy.
- To evaluate nutritional status.
- It is advised in burns, hemorrhage, leaks in the GI tract, and other chronic diseases.
- It is advised in the older people.
Pathophysiology
- Albumin is synthesized in the liver.
- It constitutes 60% of the total proteins.
- The measurement of albumin gives an idea about the synthetic activity of the liver.
- Albumin is the main protein vehicle to transport free fatty acids.
- Albumin also transports blood important components like hormones, drugs, and enzymes.
- The half-life of albumin is 12 to 18 days.
- So liver impairment is not detected until the above period.
- The main function of albumin in the blood is to maintain the colloidal osmotic pressure.
- In vascular and extravascular spaces:
- Blood.
- Urine.
- CSF.
- Amniotic fluid.
- This is a source of nutrition.
- This is part of the buffer system.
- In vascular and extravascular spaces:
- This is the negative acute-phase protein because its amount decreases in the plasma in response to inflammation.
- This decrease may be rapid within 24 hours or decreases slowly.
- This decrease may be due to the production of cytokines in inflammation.
- Albumin reduction in concentration is more noticeable in chronic inflammatory conditions.
Normal
- Source 1
- 0 to 4 days = 2.8 to 4.4 g/dL
- 4 days to 14 years = 3.8 to 5.4 g/dL
- Adult
- 18 to 60 years = 3.4 to 4.8 g/dL
- 60 to 90 years = 3.2 to 4.6 g/dL
- >90 years = 2.9 to 4.5 g/dL
- Source 2
- Premature infants = 3 to 4.2 g/dL
- Newborn = 3.5 to 5.4 g/dL
- Infants = 4.4 to 5.4 g/dL
- Child = 4.0 to 5.9 g/dL
- Adult = 3.5 to 5.0 g/dL
The decreased level of albumin is seen in:
- In malnutrition.
- After the surgery.
- In case of a burn.
- In protein-losing enteropathy.
- In uropathies.
- In the third trimester of the pregnancy.
- In chronic liver diseases.
- In collagen vascular diseases like lupus erythematosus.
- Drugs are estrogen and oral contraceptives.
The increased level of albumin is seen in:
- In Dehydration.
- Drugs are anabolic steroids, growth hormones, corticosteroids, insulin, and progesterone.
Prealbumin
Sample
- The venous blood of the patient is needed to prepare the serum.
- This can be estimated in the 24 hours of urine and CSF.
Indication
- Marker for the patient with nutritional status.
- It is a sensitive indicator of protein synthesis and catabolism.
Pathophysiology
- Prealbumin has a shorter half-life of 2 days.
- Prealbumin half-life of 2 days is much less than the albumin of 21 days.
- This is present in the serum and CSF.
- This is the main component of the CSF proteins.
- The pre-albumin binds:
- Retinol (RBP) and it also binds the vit.A.
- Thyroxin called thyroxine-binding prealbumin (TBA).
- This is a good marker than albumin and transferrin.
- This is a better indicator of liver synthetic activity.
- Prealbumin decreases in acute and chronic inflammation.
- Prealbumin is a negative acute-phase reactant protein.
- Its level decreases in malignancy, and inflammation.
- Also, it decreases in the protein-losing disease of the intestine and kidneys.
Normal
- Adult = 15 to 36 mg/dL.
- Child:
- < 5 days =6 to 21 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 = 0.017 to 0.047 mg/ 24 hours.
- CSF = 2% of the total CSF proteins.
The decreased level of prealbumin is seen in:
- In hepatocellular dysfunction.
- It is decreased in tissue damage.
- In inflammation.
- In malnutrition.
- In burn.
- Drugs like oral contraceptives, Estrogen, and amiodarone.
- Salicylates poisoning.
The increased level of prealbumin is seen in:
- In Hodgkin’s disease.
- In chronic kidney diseases.
- Some cases of nephrotic syndrome.
- In pregnancy
- Drugs like steroids, prednisolone, and androgens.
- Critical value = when <10.7 mg/dL
- This indicates severe nutritional deficiencies.