Ferritinemia with subnormal iron stores in lysinuric protein intolerance

To study the mechanism of ferritinemia in patients with lysinuric protein intolerance (LPI), an autosomal recessive disorder of diamino acid transport, we made a histologic evaluation of intracellular iron and/or ferritin in bone marrow and liver aspirates of 21 patients. We found no stainable iron in bone marrow cells. This was also the case in the liver in 8/9 of the patients. The hepatocytes were negative for ferritin particles in electron microscopy. The ferritin half-time in plasma was computed from the decrease in serum ferritin concentration during partial exchange transfusion. In the two patients tested the values were prolonged (95 and 65 min). We give evidence that in LPI serum ferritin is increased disproportionately to the size of iron stores in bone marrow reticulum cells and in the hepatocytes. We speculate that this inappropriate ferritinemia is due to impaired uptake of ferritin from plasma.