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'''Transferrin''' is a beta-globulin that binds with iron to produce [[ferritin]], which can be transported in blood. It is synthesized in the [[liver]].
'''Transferrin''' is a beta-globulin that carries [[iron]] through blood. It is synthesized in the [[liver]].
==Use in diagnosis==
The transferrin level, usually measured as '''transferrin iron binding capacity (TIBC)''' is one of the tests used in the differential diagnosis of [[anemia]],  include serum [[iron]] (SI) level, and serum [[ferritin]] level. While serum iron varies greatly, among individuals,also in response to iron intake, the other two parameters mentioned change in an [[acute phase reaction]] (ferritin rises and transferrin fslls) and thus cannot reliably detect iron deficiency in the presence of inflammation. They also do not measure if the iron is actually available for [[hematopoiesis]]. <ref>{{cite journal | author = Thomas C, Thomas L | title = Biochemical Markers and Hematologic Indices in the Diagnosis of Functional Iron Deficiency | journal = Clin Chem | volume = 48 | issue = 7 | pages = 1066-76 | year = 2002 | id = PMID 12089176}}</ref>
==Transferrin saturation==
One  way to correct for the above effects is to calculate the percentage of [[transferrin saturation]] (TfS or TSAT):<ref>{{citation
| title = Harrison's Textbook of Internal Medicine
| chapter = 106: Iron Deficiency and Other Hypoproliferative Anemias
| editor = Fauci A ''et al.''
| edition = 14th | year = 1998 | publisher = McGraw-Hill
}}, p. 641</ref>


In addition to ferritin level, test that have been used are serum [[iron]] level, and serum [[transferrin]] level. While serum iron varies greatly, among individuals,also in response to iron intake, the other two parameters mentioned change in an [[acute phase reaction]] (ferritin rises and transferrin fslls) and thus cannot reliably detect iron deficiency in the presence of inflammation. They also do not measure if the iron is actually available for hematopoiesis.
TSAT = SI/TIBC


Modern tests that circumvent this problem include [[soluble transferrin receptor]] (sTfr), [[transferrin saturation]] (TfS or TSAT), the hemoglobin content of [[reticulocyte]]s or the percentage of hypochromic cells <ref>{{cite journal | author = Thomas C, Thomas L | title = Biochemical Markers and Hematologic Indices in the Diagnosis of Functional Iron Deficiency | journal = Clin Chem | volume = 48 | issue = 7 | pages = 1066-76 | year = 2002 | id = PMID 12089176}}</ref>. Most of these can today be readily determined on automated laboratory analysis systems.
*TSAT < 20$: iron deficiency
*TSAT > 30 & TSAT < 50: normal
*TSAT > 50: iron overload
==Alternative tests==
Newer tests that circumvent this problem include [[soluble transferrin receptor]] (sTfr), the hemoglobin content of [[reticulocyte]]s or the percentage of hypochromic cells.  


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Transferrin is a beta-globulin that carries iron through blood. It is synthesized in the liver.

Use in diagnosis

The transferrin level, usually measured as transferrin iron binding capacity (TIBC) is one of the tests used in the differential diagnosis of anemia, include serum iron (SI) level, and serum ferritin level. While serum iron varies greatly, among individuals,also in response to iron intake, the other two parameters mentioned change in an acute phase reaction (ferritin rises and transferrin fslls) and thus cannot reliably detect iron deficiency in the presence of inflammation. They also do not measure if the iron is actually available for hematopoiesis. [1]

Transferrin saturation

One way to correct for the above effects is to calculate the percentage of transferrin saturation (TfS or TSAT):[2] 

TSAT = SI/TIBC
  • TSAT < 20$: iron deficiency
  • TSAT > 30 & TSAT < 50: normal
  • TSAT > 50: iron overload

Alternative tests

Newer tests that circumvent this problem include soluble transferrin receptor (sTfr), the hemoglobin content of reticulocytes or the percentage of hypochromic cells.

Likelihood ratios for common tests[3]
Test Cutoff value Likelihood ratio
Transferrin saturation ≥ 50% 0.15
Transferrin saturation ≤ 5% 10.46
A likelihood ratio > 10 helps establish a diagnosis while a ratio < 0.1 helps exclude a diagnosis.[4]

References

  1. ↑ Thomas C, Thomas L (2002). "Biochemical Markers and Hematologic Indices in the Diagnosis of Functional Iron Deficiency". Clin Chem 48 (7): 1066-76. PMID 12089176.
  2. ↑ Fauci A et al., ed. (1998), 106: Iron Deficiency and Other Hypoproliferative Anemias, Harrison's Textbook of Internal Medicine (14th ed.), McGraw-Hill, p. 641
  3. ↑ Guyatt GH, Oxman AD, Ali M, Willan A, McIlroy W, Patterson C (1992). "Laboratory diagnosis of iron-deficiency anemia: an overview". J Gen Intern Med 7 (2): 145–53. PMID 1487761. [e]
  4. ↑ McGee S (August 2002). "Simplifying likelihood ratios". J Gen Intern Med 17 (8): 646–9. PMID 12213147. [e]
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