Seasonal iron overload in Svalbard reindeer liver

Changes in liver iron concentration in relation to seasonal body weight variations and food iron intake have been investigated in 77 Svalbard reindeer by chemical and histological methods. During the winter season the body weight decreased about 43% in females and 39% in males. Liver weight was reduced about 65% in both sexes. The liver iron concentration showed little or no difference between the sexes and was 29 +/- 13 mg iron/100 g wet weight in the autumn. The concentration increased in late winter to 291 +/- 52 mg iron/100 g in animals eating iron-rich forage plants, and to 165 +/- 92 mg iron/100 g in animals eating forage plants with a normal iron content. Starving animals with a very high iron concentration of the rumen content usually had massive siderosis in both parenchymal and nonparenchymal cells of the liver. In contrast, siderosis was restricted to nonparenchymal cells in starving animals with normal rumen iron concentration. Transferrin saturation was significantly higher in animals eating iron-rich forage plants than in those eating forage plants with a normal content. Therefore it is proposed that seasonal liver siderosis is a result of a) translocation of iron from catabolized blood and lean tissue that is recovered in nonparenchymal cells and b) high uptake of food iron with deposition in the parenchymal cells.