The present investigation evaluated the serum
transferrin receptor concentration in subjects with nontransfusional
iron overload who were identified in two separate studies on the basis of a serum
ferritin level above 400 micrograms/L. Subjects with preclinical hereditary
hemochromatosis were evaluated in the first study and those with the African form of
iron overload in the second. In the first study, hereditary
hemochromatosis was identified in 14 white men on the basis of a persistent elevation in
transferrin saturation above 55%. The serum receptor concentration was elevated above the upper cut-off of 8.5 mg/L in two of the subjects, but the mean receptor of 6.1 +/- 1.4 mg/L (mean +/- 2 SE) did not differ significantly from the normal mean for this assay of 5.6 +/- 0.3 mg/L. In the same study, 60 control subjects with secondary
iron overload were identified on the basis of a serum
ferritin persistently above 400 micrograms/L, with a normal serum
C-reactive protein concentration but with a
transferrin saturation < 55%. Three of these subjects had an elevated serum receptor concentration but the mean value of 5.5 +/- 0.4 mg/L did not differ from normals nor from subjects with
hemochromatosis. In the second study, 49 black Africans with
iron overload were divided into those with or without an elevated
transferrin saturation. The mean serum receptor concentration of 5.0 +/- 0.8 mg/L and 4.5 +/- 0.4 mg/L, respectively, did not differ statistically. It was concluded that there is no evidence of generalized dysregulation of the
transferrin receptor in
hemochromatosis or
African siderosis.