Noninvasive assessment of skin iron content in hemodialysis patients. An index of parenchymal tissue iron content?

Iron overload has been described in patients undergoing chronic hemodialysis. The present study was undertaken to evaluate a rapid, noninvasive method for determination of skin iron by the technique of diagnostic x-ray spectrometry (DXS). Thirty-five patients receiving chronic hemodialysis treatment entered the study and were compared with 25 normal controls. Since pathological skin iron deposition occurs mainly at the dermal-epidermal junction in the basal cells of the epidermis, measurements were made in the thenar eminence representing mainly epidermal tissue (FeE), and in the forearm representative mainly of dermis (FeD). The mean +/- SD FeE iron concentrations were equivalent to 14.5 +/- 8.8 and 18.2 +/- 10.2 parts per million wet weight tissue (ppm) and both were significantly higher than in normal controls in which they averaged 9.2 +/- 2.5 ppm (P less than 0.005) and 10.2 +/- 3.2 ppm (P less than 0.001), respectively. There was significant positive correlation between individual skin iron determinations with the total number of blood transfusions received, the rate of blood transfusion, and with serum ferritin levels. Bone marrow hemosiderin was examined in six patients and showed a similar trend. Despite correlation only with indirect indices of tissue iron, our findings suggest that DXS may serve as a reliable quick method for noninvasive estimation of nonreticuloendothelial tissue iron deposition in hemodialysis patients suspected of having transfusional iron overload. The method may be valuable in monitoring the effects of chelation therapy.