Diagnosis of hemochromatosis in young subjects: predictive accuracy of biochemical screening tests.

The reliability of serum iron, transferrin saturation, and serum ferritin in the detection of early iron overload in hemochromatosis was determined in 120 young (less than 35 yr old) relatives whose genetic susceptibility for the disease was determined by HLA typing of families. Serum ferritin and transferrin saturation demonstrated high levels of sensitivity and specificity, whereas serum iron concentration was an unreliable test in the detection of hemochromatosis. In hemochromatosis homozygotes there was an excellent correlation between serum ferritin and mobilized body iron (r = 0.92), 1 microgram/L of serum ferritin corresponding to approximately 7.5 mg of body iron stores. For a given age, serum ferritin values were higher in homozygotes compared with heterozygotes or homozygous-normal subjects and increased by approximately 65 micrograms/L X yr, reflecting the progressive accumulation of iron in hemochromatosis homozygotes. All hemochromatosis subjects with either hepatic fibrosis or cirrhosis had serum ferritin concentrations greater than 700 micrograms/L. We conclude that the combination of serum ferritin and transferrin saturation is a reliable screening regimen for the detection of hemochromatosis and for predicting the level of body iron stores in young hemochromatosis subjects.