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Serum Transferrin Saturation Testing for Iron Overload

Serum transferrin saturation measures the proportion of transferrin bound to iron, and is derived by dividing the serum iron by the total iron binding capacity. As such, it might therefore be expected to correlate with iron burden. However, the test has been found to be lacking in sensitivity,(1) as linearity becomes questionable once saturation levels >80% are reached, and the test has not yet proven to be useful in iron estimation for patients with transfusional iron overload.(2) For patients with hereditary iron overload, the test may be more useful.(3)

Serum transferrin saturation as a test for HH

Although it may not be a reliable test for iron overload, elevated serum transferrin saturation is a sensitive and specific disease marker for hereditary hemochromatosis. Fasting serum transferrin saturation >50% in women and >60% in men, has a sensitivity of 0.92, a specificity of 0.93, and a positive predictive value of 86% for the diagnosis of hereditary hemochromatosis.(4)

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