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 proteins whose concentration increases in the plasma, and after the disease episode is over, it decreases and may become normal.

Transferrin

Sample for Transferrin

1. The patient’s blood is needed to prepare serum.
2. Try to perform the analysis of the fresh sample.
3. Can store at 4 °C for <72 hours.
4. When stored at -20 °C, it is stable for 6 months.

Precaution for Transferrin

1. Avoid hemolysis because the RBC contains iron.
2. Avoid lipemic serum.

Indications for Transferrin

1. Differential diagnosis of anemia.
2. Monitoring of treatment of iron deficiency anemia.
3. As acute phase protein.

Transferrin’s role as acute phase protein:

Definition of transferrin as acute phase protein:

1. During infections or inflammation, transferrin is considered an acute-phase protein.
2. Its concentration changes in the blood in response to the body’s immune status.
3. The mechanism as acute phase protein:
   1. There is the release of inflammatory cytokines:
   2. Interleukin-6.
   3. Tumor necrosis factor-alpha.
   4. It changes the activation and functions of the immune cells.
   5. Stimulate more synthesis of transferrin.
   6. Iron is needed for the host defense.
   7. It can bind to bacteria and viruses and prevent their growth.
   8. It helps in clearance by the immune system.
4. Transferrin as acute phase protein:
5. This is decreased in acute inflammation and raised in a chronic conditions.
   1. This acts as an acute-phase protein.
6. Its high level relates to the ability of the body to fight against the infection.

Pathophysiology of Transferrin

1. Transferrin is a major beta-globulin (glycoprotein). This is an iron-carrying protein.
   1. This is also called siderophilin.

2. The transferrin transport the Ferric ion (Fe⁺⁺⁺), and normally there is 20% to 30% saturation, which increases in iron-deficiency anemia.
   1. One molecule of transferrin binds two ions of iron.
   2. Ferrous ions bind more rapidly than ferric ions.
   3. It changes in color from colorless to pink.

3. The liver synthesizes the transferrin, and this will bind the iron.
4. This is synthesized in the liver and depends on its demands in anemia.

5. Transferrin can be lost in the urine because of its small molecular size.
   1. More loss in severe proteinuria.
6. CSF also contains a small amount of transferrin.
   1. Its function in the CSF is not known.
   2. This can be used as a marker in the case of CSF leakage.
7. RBC has a receptor for transferrin. These receptors are also present in the lymphocytes.

9. Transferrin level helps:
   1. In the case of iron deficiency anemia, the transferrin level increases.
   2. There is a low level of transferrin in the case of malignancy and inflammation.
10. Functions of Transferrin:
    1. This transports iron.
    2. It regulates the absorption of iron.
    3. It protects against the toxic effects of iron.
11. Transferrin saturation is a better index of iron saturation.
    1. Transferrin saturation % = serum iron x 100 / TIBC

Normal  Transferrin level

• o to 4 days           =  130 to 275 mg/dL
  • 3 months to 16 years = 203 to 360 mg/dL
• 16 to 60 years     =
  •  male         = 215 to 365 mg/dL
  •   female     =  250 to 380 mg/dL
• 60 to 90 years    =  190 to 375 mg/dL
• >90 years = 186 to 347 mg/dL
• Another source
  • Male = 215 to 365 mg/dL
  • Female = 250 to 380 mg/dL
  • Newborn = 130 to 275 mg/dL
  • Child = 203 to 360 mg/dL
• Source 4
  • Adult = 250 to 425 mg/dL  (2.5 to 4.2 g/L)
  • Children = 203 to 360 mg/dL (2.0 to 3.6 g/L)
  • Newborn = 130 to 275 mg/dL (1.3 to 2.7 g/L)
• Transferrin saturation:
  • Male = 20% to 50%.
  • Female = 15% to 50%

Transferrin level is increased in:

1. Iron deficiency anemia.
2. In pregnancy.
3. Use of oral contraceptives or estrogen therapy.

Transferrin level is decreased in:

1. In protein malnutrition.
2. In protein loss from burns.
3. In iron overload diseases (hemochromatosis).
4. In acute and chronic diseases.
5. Acute liver diseases.
6. Renal diseases like nephrosis.
7. The absence of transferrin is seen in the genetic disorder called Atransferrinemia.
   1. It is characterized by anemia and hemosiderosis.
   2. Hemosiderosis is seen in the liver and heart.

Value for the layman:

• Transferrin is advised when the patient has anemia (decreased hemoglobin).
• This is a better test for the evaluation of anemia, iron deficiency, thalassemia, sideroblastic anemia, and hemochromatosis.

 

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