Correction of microcytosis following elimination of an occult source of aluminum contamination of dialysate.

Abstract

A higher prevalence of aluminum-associated microcytic anemia was noted in hemodialysis unit A (n = 67) compared to unit B (n = 39). This finding could not be explained by differences in the aluminum content of reverse osmosis (RO) water or intake of antacids containing aluminum by patients in the two units. An intermittent source of aluminum contamination was suspected when water aluminum and total dissolved solutes (TDS) were measured at several sites in the water treatment facility of unit A. A one-way valve that maintained unidirectional flow in an RO bypass circuit was found missing. Intermittent pressure changes in this circuit altered the direction of water flow causing mixing of partially purified water with RO water. Installation of the valve stopped contamination and resulted in a decrease in plasma aluminum concentration from 183 +/- 12 micrograms/L to 76 +/- 7.3 micrograms/L, erythrocyte aluminum concentration from 210 +/- 31 micrograms/L to 61 +/- 9 micrograms/L and microcytosis from 58% to 8% in patients (n = 48) when measured 6 months later. Because contamination was missed in spite of water testing at the RO site, these findings underscore the importance of measuring water aluminum and TDS content at the dialysis stations. Frequent water testing at dialysis stations, familiarity with the design of water treatment facilities, and recognition of aluminum overload can lead to early detection and correction if similar types of aluminum contamination should occur.