Saturability of hepatic iron deposits in genetic hemochromatosis

The relationship of pretreatment serum ferritin and hepatic iron concentration to body iron removed by venesections was evaluated in 33 patients with genetic hemochromatosis. The median values of the three variables considered were 1,950 micrograms/L (range = 255 to 10,000), 1,175 micrograms/100 mg dry weight (range = 270 to 4,310) and 10 gm (range = 2 to 41), respectively. At basal liver biopsy 18 patients had cirrhosis, 6 patients had fibrosis and 9 patients had a normal pattern; siderosis was degree 3 in 6 patients and degree 4 in 27 patients. The results of fitting a polynomial regression of second degree showed that the curve of serum ferritin on iron removed was a straight line (R2 = 0.79, with a significant coefficient of linearity, p less than 0.01, and a nonsignificant coefficient of curvature), whereas that of hepatic iron concentration on iron removed showed a curvature (R2 = 0.62, with significant coefficient of linearity and curvature, p less than 0.01) and reached a plateau. The sigmoid model fit the curve of hepatic iron concentration on iron removed (R2 = 0.61), which suggested a saturation of hepatic iron storage capability; the asymptote corresponded to a hepatic iron concentration of about 2,000 micrograms/100 mg. In alcoholic patients (17 cases) the location of the sigmoid was greater than in nonalcoholic patients. Our results suggest that iron deposition occurs in the liver before other organs are involved and that with massive iron overload hepatic deposits reach saturation, after which hepatic iron concentration does not always reflect the amount of total stores. Alcohol consumption could slow the saturation of hepatic iron deposits.