Assessing the utility of testing aluminum levels in dialysis patients

Plasma aluminum (Al) is routinely tested in many dialysis patients. Aluminum exposure may lead to acute toxicity and levels in excess of ∼2.2 μmol/L (60 μg/L) should be avoided. Historically, toxicity has been caused by excessive dialyzate Al but modern reverse osmosis (RO) water should be Al free. Nevertheless, many units continue to perform routine Al levels on dialysis patients. This single-center study retrospectively analyzed Al levels in plasma, raw water feed, and RO product between 2010 and 2013 using our database (Nephworks 6) with the aim of determining the utility of these measurements. Two thousand fifty-eight plasma Al tests in 755 patients (61.9% male, mean age 64.7 years) were reviewed showing mean ± SD of 0.41 ± 0.30 μmol/L. One hundred eleven (5.4%) tests from 61 patients had Al levels >0.74 μmol/L and 45 (73.8%) of these patients were or had been prescribed Al hydroxide (Al(OH)(3)) as a phosphate binder. Seven patients had Al concentrations >2.2 μmol/L with no source of Al identified in 1 patient. One hundred sixty-six patients taking Al(OH)(3) (78.7% of all patients on Al(OH)(3)) had levels ≤0.74 μmol/L, the odds ratio of plasma Al > 0.74 μmol/L on Al(OH)3 was 9. The cost of plasma Al assay is $A30.60; thus, costs were $A62,974.80 over the study period. Despite RO feed water Al levels as high as 48 μmol/L, Al output from the RO was almost always undetectable (<0.1 μmol/L) with dialyzate Al levels > 2.2 μmol/L only 3 times since 2010, and never in the last 3 years. Routine unselected testing of plasma Al appears unnecessary and expensive and more selective testing in dialysis patients should be considered.