Biological Variability of Transferrin Saturation and Unsaturated Iron-Binding Capacity

Paul C. Adams, David M. Reboussin, Richard Press, James C. Barton, Ronald T. Acton, Godfrey C. Moses, Catherine Leiendecker-Foster, Gordon D. McLaren, Fitzroy W. Dawkins, Victor R. Gordeuk, Laura Lovato, John H. Eckfeldt

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Abstract

Background: Transferrin saturation is widely considered the preferred screening test for hemochromatosis. Unsaturated iron-binding capacity has similar performance at lower cost. However, the within-person biological variability of both these tests may limit their ability at commonly used cut points to detect HFE C282Y homozygous patients. Methods: The Hemochromatosis and Iron Overload Screening Study screened 101,168 primary care participants for iron overload using transferrin saturation, unsaturated iron-binding capacity, ferritin, and HFE C282Y and H63D genotyping. Transferrin saturation and unsaturated iron-binding capacity were performed at initial screening and again when selected participants and controls returned for a clinical examination several months later. A missed case was defined as a C282Y homozygote who had transferrin saturation below the cut point (45% for women, 50% for men) or unsaturated iron-binding capacity above the cut point (150 μmol/L for women, 125 μmol/L for men) at the initial screening or the clinical examination, or both, regardless of serum ferritin. Results: There were 209 C282Y previously undiagnosed homozygotes with transferrin saturation and unsaturated iron-binding capacity testing performed at the initial screening and clinical examination. Sixty-eight C282Y homozygotes (33%) would have been missed at these transferrin saturation cut points (19 men, 49 women; median serum ferritin level of 170 μg/L; first and third quartiles, 50 and 474 μg/L), and 58 homozygotes (28%) would have been missed at the unsaturated iron-binding capacity cut points (20 men, 38 women; median serum ferritin level of 168 μg/L; first and third quartiles, 38 and 454 μg/L). There was no advantage to using fasting samples. Conclusions: The within-person biological variability of transferrin saturation and unsaturated iron-binding capacity limits their usefulness as an initial screening test for expressing C282Y homozygotes.

Original languageEnglish (US)
JournalAmerican Journal of Medicine
Volume120
Issue number11
DOIs
StatePublished - Nov 2007

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Transferrin
Homozygote
Iron
Ferritins
Iron Overload
Hemochromatosis
Serum
Aptitude
Fasting
Primary Health Care
Costs and Cost Analysis

ASJC Scopus subject areas

  • Nursing(all)

Cite this

Adams, P. C., Reboussin, D. M., Press, R., Barton, J. C., Acton, R. T., Moses, G. C., ... Eckfeldt, J. H. (2007). Biological Variability of Transferrin Saturation and Unsaturated Iron-Binding Capacity. American Journal of Medicine, 120(11). https://doi.org/10.1016/j.amjmed.2007.02.027

Biological Variability of Transferrin Saturation and Unsaturated Iron-Binding Capacity. / Adams, Paul C.; Reboussin, David M.; Press, Richard; Barton, James C.; Acton, Ronald T.; Moses, Godfrey C.; Leiendecker-Foster, Catherine; McLaren, Gordon D.; Dawkins, Fitzroy W.; Gordeuk, Victor R.; Lovato, Laura; Eckfeldt, John H.

In: American Journal of Medicine, Vol. 120, No. 11, 11.2007.

Research output: Contribution to journalArticle

Adams, PC, Reboussin, DM, Press, R, Barton, JC, Acton, RT, Moses, GC, Leiendecker-Foster, C, McLaren, GD, Dawkins, FW, Gordeuk, VR, Lovato, L & Eckfeldt, JH 2007, 'Biological Variability of Transferrin Saturation and Unsaturated Iron-Binding Capacity', American Journal of Medicine, vol. 120, no. 11. https://doi.org/10.1016/j.amjmed.2007.02.027
Adams, Paul C. ; Reboussin, David M. ; Press, Richard ; Barton, James C. ; Acton, Ronald T. ; Moses, Godfrey C. ; Leiendecker-Foster, Catherine ; McLaren, Gordon D. ; Dawkins, Fitzroy W. ; Gordeuk, Victor R. ; Lovato, Laura ; Eckfeldt, John H. / Biological Variability of Transferrin Saturation and Unsaturated Iron-Binding Capacity. In: American Journal of Medicine. 2007 ; Vol. 120, No. 11.
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title = "Biological Variability of Transferrin Saturation and Unsaturated Iron-Binding Capacity",
abstract = "Background: Transferrin saturation is widely considered the preferred screening test for hemochromatosis. Unsaturated iron-binding capacity has similar performance at lower cost. However, the within-person biological variability of both these tests may limit their ability at commonly used cut points to detect HFE C282Y homozygous patients. Methods: The Hemochromatosis and Iron Overload Screening Study screened 101,168 primary care participants for iron overload using transferrin saturation, unsaturated iron-binding capacity, ferritin, and HFE C282Y and H63D genotyping. Transferrin saturation and unsaturated iron-binding capacity were performed at initial screening and again when selected participants and controls returned for a clinical examination several months later. A missed case was defined as a C282Y homozygote who had transferrin saturation below the cut point (45{\%} for women, 50{\%} for men) or unsaturated iron-binding capacity above the cut point (150 μmol/L for women, 125 μmol/L for men) at the initial screening or the clinical examination, or both, regardless of serum ferritin. Results: There were 209 C282Y previously undiagnosed homozygotes with transferrin saturation and unsaturated iron-binding capacity testing performed at the initial screening and clinical examination. Sixty-eight C282Y homozygotes (33{\%}) would have been missed at these transferrin saturation cut points (19 men, 49 women; median serum ferritin level of 170 μg/L; first and third quartiles, 50 and 474 μg/L), and 58 homozygotes (28{\%}) would have been missed at the unsaturated iron-binding capacity cut points (20 men, 38 women; median serum ferritin level of 168 μg/L; first and third quartiles, 38 and 454 μg/L). There was no advantage to using fasting samples. Conclusions: The within-person biological variability of transferrin saturation and unsaturated iron-binding capacity limits their usefulness as an initial screening test for expressing C282Y homozygotes.",
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AU - Reboussin, David M.

AU - Press, Richard

AU - Barton, James C.

AU - Acton, Ronald T.

AU - Moses, Godfrey C.

AU - Leiendecker-Foster, Catherine

AU - McLaren, Gordon D.

AU - Dawkins, Fitzroy W.

AU - Gordeuk, Victor R.

AU - Lovato, Laura

AU - Eckfeldt, John H.

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N2 - Background: Transferrin saturation is widely considered the preferred screening test for hemochromatosis. Unsaturated iron-binding capacity has similar performance at lower cost. However, the within-person biological variability of both these tests may limit their ability at commonly used cut points to detect HFE C282Y homozygous patients. Methods: The Hemochromatosis and Iron Overload Screening Study screened 101,168 primary care participants for iron overload using transferrin saturation, unsaturated iron-binding capacity, ferritin, and HFE C282Y and H63D genotyping. Transferrin saturation and unsaturated iron-binding capacity were performed at initial screening and again when selected participants and controls returned for a clinical examination several months later. A missed case was defined as a C282Y homozygote who had transferrin saturation below the cut point (45% for women, 50% for men) or unsaturated iron-binding capacity above the cut point (150 μmol/L for women, 125 μmol/L for men) at the initial screening or the clinical examination, or both, regardless of serum ferritin. Results: There were 209 C282Y previously undiagnosed homozygotes with transferrin saturation and unsaturated iron-binding capacity testing performed at the initial screening and clinical examination. Sixty-eight C282Y homozygotes (33%) would have been missed at these transferrin saturation cut points (19 men, 49 women; median serum ferritin level of 170 μg/L; first and third quartiles, 50 and 474 μg/L), and 58 homozygotes (28%) would have been missed at the unsaturated iron-binding capacity cut points (20 men, 38 women; median serum ferritin level of 168 μg/L; first and third quartiles, 38 and 454 μg/L). There was no advantage to using fasting samples. Conclusions: The within-person biological variability of transferrin saturation and unsaturated iron-binding capacity limits their usefulness as an initial screening test for expressing C282Y homozygotes.

AB - Background: Transferrin saturation is widely considered the preferred screening test for hemochromatosis. Unsaturated iron-binding capacity has similar performance at lower cost. However, the within-person biological variability of both these tests may limit their ability at commonly used cut points to detect HFE C282Y homozygous patients. Methods: The Hemochromatosis and Iron Overload Screening Study screened 101,168 primary care participants for iron overload using transferrin saturation, unsaturated iron-binding capacity, ferritin, and HFE C282Y and H63D genotyping. Transferrin saturation and unsaturated iron-binding capacity were performed at initial screening and again when selected participants and controls returned for a clinical examination several months later. A missed case was defined as a C282Y homozygote who had transferrin saturation below the cut point (45% for women, 50% for men) or unsaturated iron-binding capacity above the cut point (150 μmol/L for women, 125 μmol/L for men) at the initial screening or the clinical examination, or both, regardless of serum ferritin. Results: There were 209 C282Y previously undiagnosed homozygotes with transferrin saturation and unsaturated iron-binding capacity testing performed at the initial screening and clinical examination. Sixty-eight C282Y homozygotes (33%) would have been missed at these transferrin saturation cut points (19 men, 49 women; median serum ferritin level of 170 μg/L; first and third quartiles, 50 and 474 μg/L), and 58 homozygotes (28%) would have been missed at the unsaturated iron-binding capacity cut points (20 men, 38 women; median serum ferritin level of 168 μg/L; first and third quartiles, 38 and 454 μg/L). There was no advantage to using fasting samples. Conclusions: The within-person biological variability of transferrin saturation and unsaturated iron-binding capacity limits their usefulness as an initial screening test for expressing C282Y homozygotes.

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