UNEVEN HEPATIC IRON AND PHOSPHORUS DISTRIBUTION IN BETA-THALASSEMIA

Background/Aims: Determination of hepatic iron concentration is crucia l in the evaluation of iron-storage disease, Iron content is normally determined in a part of a needle liver biopsy and the value obtained i s considered to be representative of the iron concentration in the who le liver, To evaluate the reliability of this procedure, we studied ir on distribution in the liver of two beta-thalassemic patients, Since t he transport of intracellular iron is mediated by phosphates, we also studied the hepatic phosphorus distribution. Methods: At autopsy, a li ver slice extending from the left to the right lobe was divided into 5 1 and 49 samples, respectively, Each specimen was subdivided into two parts: one of them was paraffin-embedded and utilized for the histoche mical detection of iron; the second part was analyzed for iron and pho sphorus content by induced coupled plasma atomic emission spectroscopy . Results: The histological picture of both livers was characterized b y portal and periportal fibrosis associated with iron storage of diffe rent degree, without cirrhosis, The mean iron concentration of the liv er was 20 631 +/- 4903 mu g per g of dry tissue (mu g/g dt) and 13 901 +/- 1976 mu g/g dt, respectively, A striking variability in iron cont ent between samples was also found: iron concentration ranged from 11 537 to 32 347 mu g/g dt in the first case and from 6257 to 16 493 in t he second case, We even observed regional differences in iron concentr ation, with a preferential peripheral accumulation in both cases and a tendency the left compartment of the liver to accumulate more iron in the first case, Histochemical analyses confirmed the uneven iron dist ribution even at the act nar level, showing iron mainly being stored i n hepatocytes and Kupffer cells of zone 1 of the acinus, with decreasi ng amounts of iron in zones 2 and 3, The mean hepatic phosphorus conce ntration was 6662 +/- 1300 mu g/g dt (range: 4348-9947) and 7502-986 m u g/g dt (range: 5844-90 282), respectively, The regional distribution of phosphorus was similar to that observed for iron, A strict correla tion between iron and phosphorus content was also observed. Conclusion s: Our data show that: 1) iron and phosphorus are unevenly distributed in the beta-thalassemic liver, even in the non-cirrhotic stages; 2) a regional pattern of iron and phosphorus distribution is evident, char acterized by higher concentrations at the periphery of the liver; 3) t he observed uneven distribution of iron and phosphorus implies that th eir content determined in a small liver sample cannot be considered as absolutely representative of the mean hepatic iron concentration, The refore, iron concentrations determined in a part of a needle liver bio psy should be interpreted with caution in monitoring the efficacy of t he iron-chelating therapy in beta-thalassemic patients. (C) Journal of Hepatology.