Dialysis anaemia caused by subacute zinc toxicity

Nine out of ten patients dialysed in a satellite dialysis unit became severely anaemic over a 2-month period. The onset of anaemia coincided with the installation of a new galvanised-iron water softener in the dialysate water-supply system. An activated carbon filter was installed and haemoglobin levels returned towards previous values. Two patients on home dialysis showed similar falls in haemoglobin after the installation of galvanised iron piping in their dialysate water-supply systems; these problems also resolved after carbon filtration of the dialysis water. It is suggested that elution of zinc from galvanised iron can cause anaemia in dialysis patients. Carbon filtration removes of 95-99% of the zinc eluted.